There’s a massive price difference between the two methods (virtual DVS vs PCIe hardware) – what sort of latency figures are they, is the PCIeR card option noticeably lower than using DVS?
Yes, it’s pretty easy to run at 64 sample latency with the PCIeR card. Minimum latency with DVS is 4ms – maybe it will be OK for your usecase.
I have not used DVS in any real-time round-trip setting though – my primary experience is using it for multitrack recording from a live mixing board. Actually, we also use DVS for the audio of my church’s video stream. In that case, the DVS latency is an advantage, since we have to delay anyway to wait for the video to be in sync.