While waiting for FL/MacOS and FL Performance Mode (<insert standard when when when??? beg and plead here>), I've been figuring out how to use Ableton to play with a live band and these simple features are lifesavers.
You've probably already thought about this but here are my impressions based on what I need to do (sync clips up with a live band and provide a clicktrack to the drummer); there's room here for FL to be better than Ableton.
In Ableton, the Nudge Clip << and >> buttons nudge the playing selected clip forward or backwards by the 'global' quantisation amount, and only (as far as I can tell) the currently selected Clip, so if a clip is out of sync with the band or the rest of your elements you can fix it. It would be really awesome if FL let you nudge every playing clip simultaneously, as well as having independent quantise settings per clip (or maybe nudging based on clip groups).
Nudge Tempo does what you'd imagine but could be a bit clunky (nudges the whole track forward and backwards with an amount dependent on how long you hold it), and I'm sure FL could add some more options and improve on Ableton's options here.
A 'set downbeat' button would be really handy to automatically line up the nearest downbeat with a live source, in cases where the drummer gets a fraction of a bar off from the FL bar structure but is still on beat.
Hope that makes sense!