I'm currently running a Presonus Studio 192 interface which is USB 3.0. It has on-board DSP for latency free monitoring, allows for speaker mixing and monitor switching, I've been using it in my studio successfully for nearly three years with no problems. I was thinking about upgrading to the Quantum but the Studio 192 is going great so "If it ain't broke....."
I think the UA stuff is WAY over priced when you compare it to other interfaces, especially without their plugins!?
Being a total Presonus user both live and in the studio, I think you'd be very happy with the Quantum, or even a Studio 192 for that matter.
My other suggestion would be Audient iD44 coupled with an ASP800, you'd have a great system there!
Good luck Pat, please let me know how you get on!