A couple things to consider... I wouldn't worry excessively about noise. No one locates that first shot. It's the second one that tracks you down. Second, I would worry about ricochets. Advantage of something like the .17 Rem and the .204 Ruger is that the bullet is fragile enough that it shouldn't ricochet (it should explode instead with pieces losing velocity fast). Another advantage is that they seem to be extremely accurate cartridges.

Rest of my post somewhat unrelated... I have two rifles that will honestly do 1/2" groups from a bench at 100 years in front of witnesses. One is a Ruger R77V in .22-250. The other is a Remington 700 BDL in .17 Rem. I don't have a .204 yet; but I've been tempted for a long time. The Ruger was a horrendous shooter (3-4" groups) until I had a gunsmith work on the bedding and trigger. Was like a completely different rifle. The Remington was used. Person just had iron sights on it. I was able to test it before buying. Shot great; but had a nasty habit of going off when closing the bolt occasionally - even with finger totally away from trigger. Got that fixed. Great rifle. Shot a lot of critters with each. Wouldn't recommend them for heavier stuff where they might blow up without adequate penetration; but they are pretty amazing for smaller varmits.

[Linked Image from i108.photobucket.com]