XT v-brakes squeal like stuck pigs. I read the reviews before I bought them, but bought them anyway. I tried everything to stop the noise myself, then started going to shops. Most tried the same things, or laughed at me.
Never had a problem with mine. I "toed" them in and they worked great. Here's the way I did it:
Loosen nut holding brake pad. Release spring from behind brake arm. This causes the other spring to pull the brake arm/pad you're working on, hard against the rim. Insert a credit card along the back 1/3 of the brake pad. Move the pad around to be sure it's moved to the proper "toe-in" position. Align pad with rim, squeeze brake lever to "Mash" against rim(with credit card wedged between pad and rim). And tighten nut! Replace spring behind arm.
Repeat on the other side.
Once pads are "toed" in, check for rim clearance, adjust cable if necessary and verify both arms move equally when squeezing lever.
If they do not, tighten spring tension adjusting screw on the brake are that doesn't move in 1/2 turn increments untill they move equally.
Hope this helps!
L8R