I have played with the preview a bit (at least the first one), though had issues with importing an old FCP 7 sequence (everything was strangely scaled and I couldn’t figure out how to fix it) so gave up, though was hoping to have time to come back.
Nice to know it is still not the fastest editor, and I didn’t realize it doesn’t have a trim mode. Still it is pretty exciting with it’s node based effects editor, so if they make the editor more fully featured I think it could have a place (especially with FCP 7 Being EOL).