CrossRoads:
Looks like an interesting chip.
Supports DC to 90-108MHz operation - best you can do with SPI is 8 MHz, about 1 byte transmitted per microsecond if you can do burst of SPI transfers with no looping.
(I posted code recently that sends out 41 bytes in ~46uS from an array, added 12uS to loop thru it).
Since you have to provide at least the starting address of the locations you want to read from & write to, vs a file name associated with an SD card file, I don't see how the waveshield library will help.
Oh I didn't know about that 
I wonder if it can formatted like SD card?