Since putting this new version up I've been laying with the command set a bit myself. Didn't know it would be as useful as it appears to be.
Wow: developer uses own code ... send up colorful fireworks and hire a band! Oppps, no band needed ... it's all done with MMA
Ohhh yes, it is! Great addition. It allows mixing tracks picked out differents grooves.
My only caution on all this is that you should be cautious in importing tracks from groove files on disk. Yes, it works without problems. But, remember that if you change the groove on-disk the import may bugger up
However, grabbing bits and pieces within an existing file is just fine and encouraged.