I'll have to embrace boosting one day... My problem with it is I always absolutely hated worlds scaling with your character level - vide Oblivion, Skyrim. First thing I did was install a mod that delevels the world. I want the final enemies to absolutely wipe the floor with my weak character, and I want some noobass bandits to be ultimate pushovers once I get stronger. Nothing killed my fun in Bethesda games more than getting stronger and stronger only for bridge-dwelling bandits to also become masters of the universe wearing the best armor, best weapons, and being basically capable of killing the big baddie themselves. Or the big baddie being killable by level 1 character wielding a stick. The worst.
But in the case of Merge, it might be completely impossible to create a de-leveled experience, which requires you to travel across 3 continents "back and forth" to reach content you are capable of doing, after you hit the wall on your chosen starting continent. Would be cool as heck, but it's either straight up impossible, or would need some maestro of balance to accomplish
Especially given the fact the items/spells/skills don't have additional ranks and scaling, they are meant to be maxed out in 1 continent gameplay. But imagine if they did!
Anyhow, delusions aside, right now my small wish is to have bolstering option which gives all enemies their new abilities and which kicks in at full force from day 1. You know, for more early game hardcore challenge
I am very well versed in the ol' TES scaling debate. It was rather pronounced in Oblivion, though it didn't bother me as much as it did others. FCOM mod solved that right quick. It was much less of an issue for Skyrim, but a heavily modded setup creates its own problems. I'm guessing you use Morrowloot or Requiem? I use so many power-boosting things that I ended up creating my own methods for challenge and interest.
I have a bunch of weapon and armor mods, and I'm likely to keep the same gear for about 90% of my playthrough. I guess item progression, for me, is more about making my own top enchants. Thing is, treasure is a huge
part of what keeps me interested, that and increased abilities. I ended up relying on Ordinator to give me a sense of ability progression that would last until level 90ish.
The real change, though, was in treasure. Legacy of the Dragonborn became the core of my modlist, and the desire to fill up the Dragonborn Gallery has become the core motivation to go do all the things.
It has worked incredibly well.
Regarding total balance across all three MM games in the merge.
(Completely hypothetical. I have no plans to do this to MM7 Refilled
It's a tricky puzzle. The openness of the Merge is a large obstacle. Traditionally, one would simply decide what locations are going to be at what level. Enrothian goblins start at level 80. Erathian Goblins start at level 40. Jadamean ... pirates (?) start at level 1.
But what if someone wants to start in Enroth? Or do what I did, and start in Enroth until level 20 (get promoted, and air/water mastery) then move to Jadame? Maybe partway through Jadame, I take a break and go to Antagarich because my Monk needs Unarmed training. Need to go through EI, Harmondale, Erathia, Tatalia, and Evenmorn. Everybody is going to have their own path through the continents. Heck, the vanilla one is to start at Jadame, then go to Erathia after Escaton, then Enroth after Lincoln.
It would be really cool to have to criss cross between continents. However, that would require someone to dictate the path. Even if you were to create clusters of content .. say ... You hit level 15 in Jadame. You've cleared out Daggerwound and Ravenshore, but everything else is level 30+ content. Say you get to choose from New Sorpigal/Castle Ironfist or EI/Harmondale. Maybe it's balanced to where you have to do the first two zones in all three continents before you are leveled enough to handle anything else in the continents.
My vanilla strategy in MM8 was to, upon arrival in Ravenshore, immediately head to Alvar, Garrote Gorge, and Murmurwoods. I got quests in Alvar (including the Personality potion for my Dark Elf), picked up a dragon follower in Garrote Gorge, delivered two flowers to the opposite sides, leveled my dragon to Master Dragon for flight, turned in the book in Murmurwoods for Priest of Light promo, flew the dragon around snatching up every high level chest, and dipped down to free Cauri and secure my Dark Elf promo. The level of the inhabitants was irrelevant. There was a "wall", and I flew over and around it.
I think, since there is such a diversity of both playstyles and paths through the Merge, the best option is to allow you to tailor the difficulty of the foes to whatever order you want to take things. That's what's so great about the on-the-fly boost setting. If I want those goblins in New Sorpigal to be just as weak as when I first fought them at level 1 so I can revel in my new power, I can turn off the boost when I return to my home zone. If I want 100hp goblins and apprentice mages with 40AC, I can leave it on.
Now, extending item and skill powers from the level 60 range of normal endgame to the 150ish of Merge endgame, THAT would be quite the feat. You'd have to either create new tiers of items (probably hard-coded into the engine) or further stratify the existing tiers (technically doable). A lot of treasure drops would have to be hand-adjusted. A T4 drop as a boost for a level 15 party would now be intended for a level 80 party, and woefully out of place.
It's a lot of work, but this is actually fairly feasible. The tiers are already somewhat overloaded, bearing three games worth of items in each. You'd have a tough time getting past the stair-step problem, of the power jump between those tiers. In particular, T1 vs T2. Let's say you make T2 the equivalent of vanilla T3 or 4. Does that mean you're stuck with T1 Crude Swords and Rusty Chainmails for an outsized amount of time? If that first Trollish Warsword, or Steel Chainmail (T2) is much more powerful than vanilla, it creates an even larger power disparity should you acquire one ahead of time. The same 6 tiers would be expected to cover around double the levels -- 150ish vs 60-70ish. Of course, at some point, the item tiers become replaced by artifacts.
It would have to be done with an assumption that the player is criss-crossing continents constantly (heh fun phrase), almost striping across the content. Artifacts would be relegated to endgame areas, and wouldn't appear until probably over level 100, may be 120. You'd probably want to remove the "free" artifact locations in Jadame (willow tree, rock, fort wall, etc), but hand place some (still random) in places like the Memory Crystal dungeons, the elemental planes, Nighon area. You'd have to hand-craft all the monster stats to adjust to the new design schema. Liches are now level 100-120 critters, stuff like that.
Skills ... hoo boy. I don't even know what to do about those. Except maybe make Expert take rank 7, master rank 15, and GM rank 25, or something, with commensurate cost increases. Would that be enough to extend it out? Can that easily be done?
Most importantly, how many players would find all this constraining and heavy handed? Well, I guess those players would play a different mod.