Shimano BR-M505's vs. Avid Juicy 3's

[bwalton]

I am looking at two different 29er bikes. The $1,100.00 2011 Specialized Rockhopper Expert 29er is equipped with Shimano BR-M505 hydraulic brakes with 160mm rotors and the $1,300.00 Specialized Rockhopper Pro 29er is equipped with Avid Juicy 3’s with 160mm rotors.
Question 1:
Without getting to far into the debate of which company produces better products, are the J3’s and upgrade over the Shimano M505’s?
I currently own one set of Avid J5’s and one set of J7’s, both of which have had the dreaded turkey warbler squeal caused by sticky pistons. At one point I was at the end of my rope with these Juicy brakes until I learned to coat the caliper pistons with automotive silicon brake grease before pressing them back into their bores. This silicone grease acts like a make shift dust shield and prevents dirt and brake dust from working its way under the seals and jamming the pistons.
Question 2:
I live in a dusty area and therefore am concerned that the Shimano M505 pistons/seals will get contaminated and jamb the pistons like the Avid pistons.
2A) Does Shimano sell rebuilding kits for their calipers? If not, how does a own go about freeing a sticky piston that has dirt lodged in its seal?
2B) Are Shimano Brakes easy to bleed?
2C) Are Shimano bleed kit reasonably priced?
2D) How do these mineral oil hydraulic brakes perform in 35 degree weather? I plan on using this 29er for commuting and smooth mountain bike trails.

[mitzikatzi]

Bleed kit 1
Bleed kit 2
Bleed kit 3
Bleed kit 4

take your pick

Maybe this will help. Taken from another forum. The poster is a bike mechanic in a shop and a keen MTB rider too

Ah, the old sticky-piston syndrome. Wheel & pads out, squeeze the lever a few times to push the pistons out a bit. Wrap a rag over a small screwdriver & wipe the sides of the pistons clean. Lubricate with a light spray grease if you've got some handy, or even just a bit of wet chain lube.Push the pistons back in with either a flat screwdriver or a 10mm open-end spanner - the latter especially if you have Hayes or Avid brakes which have a central post on the pistons to locate the pads. Pushing on this post is likely to bend it, then your pads will be out of whack.

Give the lever a few pumps to make sure the pistons move freely & equally. If one moves more, brace against it with your screwdriver or spanner while you pump the lever. This should free the sticky piston. Once they're working nicely, push the pistons back in, clean up any excess lube & replace the pads & wheel. Pump the lever a few times to settle the pad contact gap, loosen the the caliper mount bolts to allow the caliper to centre when you squeeze the lever, hold it on & tighten the bolts & you're set to ride again.

as for parts go to Shimano Tech documents work out what you want (part numbers) go to LBS and order.