Using the UMC ASIO driver, I lowered buffers to 128 and reported round trip latency was 4.4ms.

I currently have the ASIO latency buffer set at 64 and that's producing about 6-7ms of round trip latency

My biggest concern is if I can get a low enough round-trip latency to play virtual instruments?

In the end the latency can generally stay under 10 mS. If there are many tracks playing, with realtime effects, that old 19 mS round trip latency is back, looking not so terrible

This is not the same thing as running many VSTIs in a large project, but it shows that if tracks are frozen and load is not too heavy, that the interface has the ability to play at low round trip latency for tracking.

Maybe - as well as with any USB interface, which is to say “within limits”.I can live and play in time with a 10 mS round trip latency

While it takes some fiddling with the software to get a good balance between low latency and lack of crackling, it works as it should

The device seems to work as I intended it to, and time will tell if there are audio quality issues or other concerns I haven't thought of.

Maybe - as well as with any USB interface, which is to say “within limits”.I can live and play in time with a 10 mS round trip latency