Gentlemen - Thank you for your perspective!
I shall attempt to avoid a mixer if at all possible, using instead the I/O's of the interface. "Compromises and complications" ... shudder!!
Having a separate audio interface and mixer does cause an extra bit in the chain as well as expense but there are mixers that have the audio interface functionality built into them and allow you to do all things you wish. you can also use these desks as analogue summing units to add a bit something back into your mix. Don't completely Bin the idea, do a little research.