Too long, even at 1/4 of Long War's length?
Quite possibly. Although it's starting to sound reasonable.
Does it actually balance properly for that length? I remember long war had an option to make it shorter, but if you used it the balance would go way out of whack because not everything scaled properly (for example, 50% of all missions would become exalt missions, because they didn't scale).
It's a good question, but Long War Rebalance is honestly a new game at this point.
By default it's half of Long War length, and the pace feels ok to me. Mind you, it *IS* long and I'll make pauses in the campaign. But the pace of new threats and novelties seems about right.
The modmod has been refined for years so it's a reasonable assumption that even the "doubly shortened" option is reasonably balanced. I would give it a try.
To be more precise the author keeps trying things out, so now and then the balance ends up a bit worse than the version which came before.
But OVERALL the modmod has followed a "betterment path", shall we say?
I've played several versions, with long pauses after each, and each time the experience felt improved somewhat, or even vastly improved.
With the current version I'm even satisfied with Gunners, finally.
Mind you again, it will require some testing of your own to find your own comfort zone.
Classic difficulty starts decently easy even for a new Rebalance player, I think, but if you don't know what you're doing you'll be outpaced after a while.
I *might* be skilled enough for Brutal, at this point, but Brutal surely requires a "sacrifices" oriented style of play, so for now I stick with Classic with a few Second Wave options to make it a bit more difficult.