What are you going to do with the saw is the big question.
For me, re-saw is the primary purpose of a band saw, and I don't just mean book matching boards. The band saw is part of my milling process.
It appears that the G0636X might come with a few more polished feature. Fence and trunnion, but I would hope there would be more in the frame also.
In the end though, I'd go with the G0548. 500 more FPM of blade speed, more weight, and a larger rotational mass, is pretty darn attractive. I'm confident that with some tuning and playing around with the guides, the G0568 would be a fully capable re-saw machine. ( I would machine a different style of guides for either machine, but that is a personal preference. )
It looks like the G0636X may come more re-saw ready, but I'm in the bigger is "usually" better camp.
"The first thing you need to know, will likely be the last thing you learn." (Unknown)