FWIW,
 
Last night I did some tinkering, and I found the source of the sluggishness in MIDI throughput:
 
Even though I was using the -noaudio flag, apparently the number set for audio latency still applies.  So, I simply made the audio latency 1 millisecond and MIDI now works properly (it was 70 ms to begin with, definitely a noticeable delay if youre trying to play keys...)
 
Thanks again,
rs