The fastest way to get files from the SD cards is to use a card reader in laptop or desktop system. In my card reader I think 4gb will take 5-6 minutes if I remember correctly. It depends upon the reader though.
It is possible to use the USB, but it is way slower. This is done on the host computer using an application called ActiveSync. If the PDA has wireless you can also ftp the file to a computer running an ftp server. It is also possible to copy the files to a network share. Copying wirelessly is plenty fast enough.
24/96 is roughly 3 times the data rate of CD.
24 bits = 16 bits times 1.5
96kHz = ~2x 44.1kHz (roughly 2x)
CD rate is about 10 mb/min, so 24/96 is about 30 mb per recorded minute. 60 minutes would be about 1800mb. So to a 4gb media expect about 2 hours.