The differences are interesting - with the wrapped VST, I get absolute sample accuracy. With the RTAS version, it's not as simple as a case of consistent latency (or whatever latency is called when it comes early - earliency?!) as there is significant variation between triggers. At 120bpm, My M5v1 shows consistent latency of 11 ticks for the VSTW and occasional (unpredictable) latency of 6 ticks (it's either six ticks late or bang on time... weird) for the RTAS.With the HD system, there's only about 1/4 of a millisecond delay between a gridded quarter note click and Machfive2 playing quantized MIDI quarter notes of the same click sample. So it's not what you'd call sample accurate. But it's very short, and it's consistent enough that you could probably dial in a MIDI offset if it was ever an issue.
I'll stop caring about the issue if it's just me with the disastrous RTAS problem, and put it down to processor/system/Windows.
I just can't get over the fact that it works as a wrapped VST. What extra information is being used that the RTAS is ignoring?