Not sure I understand the value of fpga on a streamer, which should be a very simple device.
The unit I am now using also has a fifo buffer and uses 2 clocks, but I'm not sure they qualify as OXCOs. They are easily user replaceable and I am now using two Accusillicon clocks, a 45 and a 49. Though the Accusilicons are very good, I may very well move on to even better clocks. The Accusilicons, and any other clocks I may use, publish their phase noise data, which gives at least a hint as to their quality. What is known about the clocks in the Gaia? Also the PS in the unit I'm using is much like that on the digital side of the 005 and is further upgradeable.
In any event the first thing a DDC has to do is clean up the USB stream.