baseband bandwidth of up to 270 KHz with I/Q serial data output.
I think you are not meaning that those 270 kHz should be sent to the
serial port
of the PC, are you ? An USB1.1 or USB2 interface would be much more
appropriate,
IMHO. Given your capabilities in preparing PCBs and kits, why don't you
take into
serious consideration a kit with the AD9874 ?
The availability of the hardware part would be an incentive for the
software writers,
I am sure.