Given the downgrades in CueMix 5, would TotalMix FX bring a lot more to the table as far as the DSP and routing is concerned?
If your intention is to use this as a multichannel DAC with a computer front end then you probably want to do all your routing and DSP on the computer. Earlier in this thread there were comparisons with the onboard EQ and other DSP functions that were more limiting than previous hardware but that is more a concern if you are a musician and not using it for home audio. This omitted functionality was moved over to the Cuemix software which has mostly improved in my opinion.
Effects are disabled at 4x sample rates (176.4 or 192 kHz), could be a deal breaker?
I believe this only applies to the onboard effects. Shouldn't be any limitations with any processing coming from your computer.