My previous character became so over powered way to quickly, though I have to take some blame there. I maxed out every levelup (with x5 bonuses) with caps removed in MCP, that along with me doing side quests and exploring a lot as I always do the character was way overpowered for the Main Quest. So I started a new one with the trainers only thing. Also I've never tried a light armour or destruction focused character so I went with that.
The trainers thing doesn't feel out of place to me just different, in that you don't see any difference other than never increasing a skill while fighting/jumping etc, and it also means you get to choose when to become more powerful provided you can afford the training and once a skill gets high enough you need to find a capable trainer. I chose a version of the mod that locked the level up bonus at x3.
(SLATE Leveling Mod -
www.nexusmods.com/morrowind/mods/43498/)
I combined that with another mod that doubles the price of trainers, hoping to make the leveling up/training slower, via the "Balance Training.esp" from "Mod of Balance" (
www.nexusmods.com/morrowind/mods/504/)
Also used No Daedric Drops (
www.nexusmods.com/morrowind/mods/45403/) to avoid being flooded with Daedric weapons and money from them.
The end result wasn't as drastic as I had hoped, though again partly my fault as I'm happy stealing anything that isn't nailed down and I use a mod that gives traders more money (More Barter Gold -
www.nexusmods.com/morrowind/mods/40053/) as I don't want to abuse things like Creeper the trader who gives you full value but also feel many traders should have enough Gold to afford a glass sword for example.
So with leveling up essentially tied to money and money not being that hard to get if willing to steal (even without Daedric drops) it meant you could still level up fast, though there's a big but here, leveling up now became controllable, even optional.
Due to being a magical kleptomaniac I as always became insanely wealthy except I now rarely leveled up unless I wanted to or felt it appropriate. For example before taking on Dagoth I was on level 18 but decided I'd give myself 2 more levels not because I felt I needed them (I met Vivec on lvl 14 and could kill him effortlessly though he could 1-shot me) but because it felt like getting ready for the big fight was fitting.
So I guess the biggest change from this ended up being able to prevent leveling up uncontrollably, which meant being able to explore and do as much as I wanted without becoming to powerful, level/skill wise, for the main quest.
It also removed any urge to kill random things for the sake of "XP" or jumping up hills or while traveling as that no longer gave "XP", having the urge to do those things removed was a nice change even a relief at times.