That would actually be so great, ie in theater shows to follow lights transitions !
By the way, while adding separate in and out timings, it would be nice to augment the range a bit. In theater configurations, it could be usefull to have a 30s transition !
And, very important for something still missing with transitions : that the clip being faded out goes on playing while fading out. FOr now, when you launch a new clip with a transition, the old clip pauses, which is so ugly !
For now, since several years now, I cheat there with an external OSC sequencer (often made with Max/MSP) which sets layer Transition time just after launching the previous clip... But it's really tricky !