Thinking of this change myself.
The large gaps in channels being a bad thing is related to how you have your setup universes defined. E.g. did you set up 64 universes of 512 in setup and therefore are transmitting 32000 channels 20 times a second or 40 times a second? Perhaps it does not transmit if there is nothing there, but I understand the file size is bigger for the fsew because it is accounting for nothing in all those other channels e.g. sending zero.
I've been on absolute for years as I think dealing with universes is a big pia, oh did I go over 170 nodes, oh I have to skip a universe, over 340 nodes, skip another one or 3.
With the check sequence you can get notice of this before you have to head scratch it.
I tend to like props in an area or concept to be close together channel wise. And over the years that has lead to a hodge podge of channels for this prop crammed between these two props etc. I had a LOT of cascade moves last year.
The chaining in Xlights did not work well last year, this year might be all fixed up judging from the lack of support posts on the subject relative year over year.
I may do a controller or two on universe this year, but it is just as easy for me to skip a few thousand channels currently.
If you are using the xlights to controller upload and the xlights to fpp upload, then your universes get defined for you if you skip say 50 or a 100 universes to "leave" room.