THe USB vs I2S debate if tremendously overblown. While superficially I2S seems to have an advantage by seperating out the clock, the implementation of I2S has been horrible. There is no standard and implemtation is different by every vendor. I wouldn't be afraid to try it, it may sound great. But the truth is there is a tiny advantage and implementation matters much, much more. Innuos buillds their streamers around USB and I'd put that up against any I2S. My new Grimm uses AES/EBU and is fantastic. Bottom line is, go with the one that the manufacturer built the system around.
The negative press for USB is all about selling other options and lots of keyboard "experts" have picked up the sales pitch and run with it like the key to higher knowledge and sexual gratification.
Finally, choosing a component based on whether is has I2S support or not is like picking a state to move to based on the color of the license plate. Focus on what really matters, not I2S.
Jerry