Hi
PiaF has only been out for about six months. We are not supported or sponsored, unlike others, nor do we have anyone on salary fulltime, we cannot afford that, and we all have to do day jobs. With that in mind, I think we have done OK, coming up with a system that is reliable, reasonably secure, and by default we do not expose the name, extension number and status of every phone on the PBX to anyone who cares to look.
Therefore given the resources that we have, we have chosen the Aastra 5i range of phones to concentrate on, and try and provide functionality to that phone really well, rather than try and support every different type of phone out there. Fortunately we were able to get a 57i cheap at the recent FreePBX training to play with.
If you are going to adopt PiaF as your PBX to resell, then I suggest that you steer your customers towards the Aastra 5i series of phone - from my experience, they are quality, will not let you down, and at least you have a greater source of knowledge, support and information of other peoples experience with them here.
If you do prefer the Polycoms, Grandstreams et al, then that is fine too, just bear in mind that you may have to work out how to implement your own features yourself.
Joe