Ammunition availability is difficult to predict. It was only 5-6 years ago that .22LR was impossible to find. While I do not think it will become as rare as Scrat's Ice Age Acorn, I do think the .327 federal is established enough that it will always be found at cabelas/bass pro, but not necessarily at Wal-Mart. And as "Reddot" said, the .327 will shoot other .32's. Be aware that the .327 is a high pressure cartridge and the muzzle flash and blast will be noticeable in the SP101, as indeed the .357 would also be in the SP101. I have a friend who has a .327 and he likes it as a defense cartridge, because he claims that if he misses, he would still be likely to set the assailant on fire. That being said, I believe the SP101 in the 32 chamberings, is one of the best woods, trail, camping, tackle box, etc. guns out there. With handloading there is even more versatility - from self defense to plinking.
I have an SP101 chambered for .32 H&R. I like it very much. No, the trigger is not even remotely as smooth as S&W, and yes, the trigger pull is hard, and not too much can be done about it. However, trigger pull is subjective and personal. It's just one of those things that you have to make your own decision about. Wilson and Wolffe make spring kits to lighten and improve the trigger. I think it is supposed to bring the trigger from 12-14, down to 10 pounds. The SP101 is easy to disassemble and installation should be within reach of the home gunsmith. So far, I have not changed the springs. I'd rather deal with the heavier trigger pull than risk reliability and ignition problems from lighter hammer springs. But, again, that's a personal call, and the trigger, as is, has not been a significant problem for me.