Suppressors don't affect accuracy in a negative way. Remember the bullet never touches the inside of the suppressor so there is nothing to contact.
They improve accuracy if anything else. The added weight to the muzzle of the weapon acts as a counter weight, so you'll have less recoil which in turn produces less flintching, you'll get back on target quicker. You won't have to worry about muzzle blast which will reduce flintching caused by anticipation of the blast. So it's a win, win.
Some people say that it influences velocity. It doesn't.
Another Very good company that I can attest to is AAC (Advanced Armament Inc) Advanced Armament :: Home
I have one of there 7.62sd cans and I've shot side by side with a work rifle with an AWC can on and bystanders said that mine was noticibly quiter and it's a quick detatch can, vs a thread on. If mine were a thread on it would be even more quiet. The AAC cans are cheaper, lighter, have a better dB rating and better made.