Do you hard core climbers raise your seat for climbing up the trails? (Same as mt. bikers do for climbs)
Coming from the perspective of a muni beginner but longtime MTBer, I would say you want your uni seat high enough to get good leg extension, but not so high your knees “lock” or move backward. You also don’t want it so high that you don’t have the free movement needed when you’re standing on hills. Seat height is real important, besides the technique aspects it also has a direct impact on knee & quad fatigue, and can injure your knees if not positioned correctly.
I don’t think mt.bikers raise their seat for climbing as much as they lower their seats for descents. The problem with climbing on a bike is that if you get out of the saddle the tendency is to put your weight forward which takes it off the back wheel. On a descent it helps to have your weight lower, and sometimes further back. I have lowered my seat just to get it out of the way so that I could easily slip behind it on seriously steep descents in Moab.
In general on my MUni I like to have the seat a little lower than on my road uni. The only time I move it is when I change crank length.