@Vando. Man, you're in some serious mods there on your topic. Too f***ing hardcore for me :P
Well, let me tell you what I have decided with my XT's suspension:
Front: I won't swap the fork, because a fork that has a larger diameter won't fit because of the 23L Acerbis tank (when I turn the handlebar at maximum, this one has 1,2 mm left, and the 43mm or 48mm fork has also a thicker triple clamp...). What I will do, is change the springs with progressive ones for now, and that's it, cause I don't have any info on where I can get some emulators...
Rear: for now, I will fit a progressive spring. Hyperpro makes them (however, their customer service skills pretty suck) and hopefully I can get a stiffer one (they have a kit with fork springs + shock spring + oil at about 200 EUR).
Wilbers can deliver a rear shock that increses the height of the bike with up to 40mm (and it's plug and play, no mods necessary), so this part is very easy, but I will consider it in the future only.