The 75ps figure for direct I2S is strikingly similar to the 75ps of the DIR1703 spdif receiver, which claims similar result and is based on TI's spact system. A system originally designed for adaptive USB.
For the rest, nice summary. I did a similar exercise a few months ago here : http://www6.head-fi.org/forums/showthread.php?t=141238 The replies there point however to the possibility of achieving asynchronous transfert.
There are also the (dubious ?) claims of Wavelength (Gordon Rankin), saying that it is possible to get asynchronous transfer out of a PCM2707. See here http://db.audioasylum.com/cgi/m.mpl?forum=pcaudio&n=228
