OK, you want a screaming TNC -- don't forget the G3RUH on steroids made by the Baycom guys and gals in Deutchsland: http://www.baycom.org/bayweb/tech/eppjnx/eppjnx.htm
Warning -- they are not inexpensive! But they are designed around Flexnet, if memory services.
Unfortunately, they don't have I/Q in/out, which rules out the use of a lot of the newer low-powered 23cm/13cm-capable transceiver-on-a-chip solutions for the RF portion.
I'm talking to the folks at ViaSat about making their DVB-S2 modulator/demodulator chip available for low-quantity amateur radio use. If I can talk them into it, we'd have a banging solution for both "packet" and Digital ATV -- the transport stream in DVB-S2 is bits, after all. Whether they are IP-based or not isn't particularly relevent.