@antigrunge2
Other than the obvious advantage of asynchronous connection you pointed out, I can think of couple of reasons why USB still considered a better option for servers. There is no standardized connector with i2S protocol, some uses RJ45 and others using HDMI. Both AES and BNC (SPDIF) has sample rate limitations (upto 192kHz) unless you’re using dual AES outputs which is very rare. Not to mention jitter which if not addressed properly can become a detriment to a bitstream.
IME, The Ethernet based DAC/Server all in one device is the way to future. The brilliant designers at Merging Technologies and Aurender has proven that you don’t need an external or separate server with ginormous processing power to run Roon Core or to run your favourite player software to hear music files. The whole separate server from end point (renderer) is a propaganda by ROON to fool people into spending money and jumping through hoops with tweaking gadgets to get data stream from Server to End Point (player or renderer). Just think about it, how many folks are benefiting from this grand scheme of running a Roon core on a separate server.