I want to say I'm very happy that you are focusing on improving the channel changing. You definitely solved the problem with MC getting bogged down by rapid channel changes.
There is a remaining issue that occurs with a single channel change. In short, it's still way slower than WMC, but here are two specific things that might help, and these occur with all combinations of DirectSound/WASAPI/ROHQ/ROStd/VideoClock on two different machines so I don't think it has anything to do with audio/video settings:
1. When the channel is changed, all video halts and audio goes away, as expected, but after a second or so, both video and audio from the channel I am changing from resume momentarily (for as many as 2 seconds - this seems like a waste of resources, and it is distracting) before it jumps over to the new channel.
2. When switching to a channel that has a different aspect ratio, the new channel will sometimes play for several seconds (sometimes as many as 10 seconds, but usually less) in the wrong aspect ratio before correcting itself.
Oh, and one little thing - wrapping doesn't work. So if I'm on channel 51.3, my highest channel, and hit channel up, it doesn't do anything. I'd like to end up on channel 8.1.