In an effort to transition between seamless looping generative visuals on a paused/looping timeline (described in this feature request: (viewtopic.php?f=29&t=36265 ) I have started using timeline player tracks containing the visual parater for each surface. However the transition length can't be edited on the conductor and still needs to be set in the timeline cell in the grid. It also means any differing transition lengths will need to be whole new duplicates of the same timeline with differing transition times.
If there is no interest in implementing something like the free-running montage tracks linked above (which imo would be a more elegant solution) or somehow giving generative visuals their own special timebase then perhaps adding transition controls to the timeline player track is another option. However considering how many parameters are potentially within a timeline in a timeline player track, a simple x-fade control like on montage tracks could get very confusing/heavy etc. and potentially clash with the transition rate on the timeline cells themselves.