Interesting, since I upgraded a PK-900 for the sound card interface in March and preparing to update a PK232MBX (1989 version) for latest firmware and sound card interface.
Minimizes cable interfaces to the radio(s) -- I can run either sound card modes OR the PK-232 modes native.
Much easier to use with 2 radios (PK-232 and PK-900) -- than sound card.
RTTY (Baudot) still solid with PK232 -- and Pactor -- well you will spend more on the PC upgrade to run that IF it is ever offered!
Ham Radio Deluxe and the new CCS Radio Opeaitons Center are good software applications that support all of the switching!
Want to see what $370 buys today?
US Interface -- The Navigator -- LOTS of surface mount parts inside!http://www.usinterface.com/
BTW, I have many home built sound card interfaces (Icom design; N9ART board, etc.) .. yet I see > $100 spent for $10 in parts -- to each their own.