I think it can be acceptable, and we have done it in the past with good results. Can get tricky keeping track of it, so it becomes incumbent on the "PiF Crew" and individual to police it and make sure it isn't abused. As long as overall value brought to the thread evens out. (e.g. one manix for one pm2 = good.... 3 or 4 decent folders of varying value for a really nice fixed blade, etc. = good... 3 rando ganzos, a remote control for a tv no one owns, and a kershaw for a Sebenza = not so good
).
The trick with that will probably be limiting it so it is manageable by the group overall. It gets too hard to create a "bank" list you have to follow with the main list. So, here and there is good... but it gets hard to track if you are dropping 10+ items and never claiming anything. So, case by case I guess? Hate to tell people "don't PiF too much without anything in return," because that kind of selflessness is really the foundation of the idea... getting good stuff you aren't using in the hands of people that could use it.