What limitations do you see? Any hw/technical limitations or is this more concerned with availability?\
buying another board an all new hardware,
we already have all the hardware (except the failsafe rc part)
so if we are going with a paparazzi board we will need to drop all out hardware and start over, or is there a possibility to integrate our own modem, gps servo controller and stuff with the paparazzi boards?
Of course you can integrate your modem and GPS with paparazzi.
- Modem should be trivial (probably nothing to be done here at all as long as your modems can provide a transparent, serial-like, link and don't need any fancy in-the-air configuration).
- GPS should not be a really big deal either (although the paparazzi NMEA parser is not really good and nobody uses it afaik). So you would probably want to have a look at the parser and make sure it works always and does not hang up on unexpected packets. NMEA is not really nice in my (and a lot of other peoples) opinion anyway.... but that is not the point here of course.
- Your servo controller you would very likely not need at all, since that is already directly on the paparazzi boards.
Nevertheless, personally I think it would be nice to have support to run all the paparazzi stuff in linux userland. That being said, I don't think this is a very good idea in a lot of cases. (You loose tight control over timing, you should probably use a RT linux, etc.)
Imho it often makes more sense do do the sensor interfacing and fast estimation/control loops directly on a dedicated board and only do higher level (navigation, payload, perception, etc.) on a (especially when it is a non-realtime) linux board.
Cheers, Felix