I would question the vaildity of some of these statements.
With a moderartor on both rifles a .17HMR is infinitely noisier than a .22LR. That doesn't matter whether it is bolt action or semi auto. The fact is that the speed of sound is broken with a .17HMR whereas it isn't with a subsonic .22LR round. If you are talking about using the likes of CCI Stingers in the .22LR then the difference is obviously negligible.
However, for rabbits, I believe a good set up with accurate sub sonic ammo will be good out to 100yds, if you are good enough. I am not, with headshots, so limit myself to 75 yd