personally i would go w/ the bostich mIII because i have used it for two and a half years in my rental shop and have yet to have any significant problems...(other than the occasional jamb and normal wear and tear)...i have yet to have any experience w/ the p-c...

as far as wich is better nails or staples...it really is personal preference because i have used both and they both hold equally well as proven by how difficult it was to pull out mislayed boards w/ either type of fastener...also the national office for my rental center did a test to see which worked best and found out that it was a wash they both performed equally well

i hope this helps

SO far I have laid 4000 SF with my bostitch stapler. THe peices are really hard to remove once nailed down. On the other hand, I think PC makes a multiuse tool that can be converted from an angle nailer for the field, to a face nailer for when you get close the the wall and finishing the job.
It uses cleats instead of the staples. So it would be a matter of which you want to get, if you get the sapler, plan on getting a finish nailer as well, or plan to nail the last few rows by hand, which is rather a pain since you need to predrill the holes first and then nail in the boards, and if your a lousy shot with a hammer like me, can be pretty disasterous when you miss. The PC tool can do both jobs. Then you need to consider the cost of fastners as well.

you will also need to keep in mind the cost of both the PC nailer and the conversion kit...if you want more bang for your buck...pick the nailer/stapler you are most comfortable with plus a finish nailer...at least then you can use the trim gun to install your base and shoe