Actually, OctaMED SS is a bit of an Achilles heel for UAE. No amount of fiddling around with UAE's settings can get rid of the lag between pressing a key and hearing the sound; something no genuine amiga suffers from.
We have spoken about this before, as I used WinUAE in the recording studio before, I did get the latency down below 10ms, and certainly low enough to be imperceptible to my feeble human ears

Though I tried to use real hardware as much as possible for that "authentic" 8bit audio... Very few will ever appreciate the effort I went to

Of course, when it comes to basic playback of a completed track, it (understandably) performs very well, particularly on many-channel modules.
Yeah, makes a great sequencer