I have the Kenwood THD-7E (the same as the one you're considering but for the European market). I've had the radio for over three years and have used it extensively as a talking tool, packet radio (to local BBS's), APRS and SSTV. It has proved to be one of the most resiliant transceivers I've ever owned and would happily purchase again!
The TNC implementation is such that you can use it as a 'standard' TNC for connection with a terminal emulator to talk with BBS's or other packet stations (this means you can also use WinAPRS, UI-View and the PocketPC APRS programs whilst having data from a connected GPS automatically forwarded THROUGH the PC port on the Kenwood). You can also use the 'built-in' APRS functionality where you don't bother with a PC connection, rather the radio itself uses it's own APRS facility rather than an external TNC APRS program. It is also possible to allow received APRS stations to load as waypoints automatically onto the GPS! Feel free to drop me a note to my other ham radio callsign:- email@example.com