SC will have the advantage of everything being designed, so hopefully variety and the number of things to do will be better. Relatively, size will suffer though.
My main concern is that SC's going to wind up feeling too small. I think that will likely work to its advantage somewhat because there will be more opportunities for interaction. I know for myself, I would rather play in a smaller game universe that is full of busy stuff going on instead of a giant empty universe. Kind of similar to large vs small maps in AH.
Until it actually gets up and running beyond the combat arenas I don't think it can be judged in any meaningful way though.
I haven't gotten ED because it looked to me like a more polished version of the Evochron series, and that got stale for me too quickly to justify getting into ED.
The tricky part with games like that is, no matter what the actual gameplay is limited. At the end of the day it all boils down to going from point A to B with or without cargo (trading vs exploring), collecting resources or mining, or fighting something. SC's also going to have the FPS portion which will likely help the game from getting too repetitive.
If the way they implement that gameplay is fun, it works. They can come up with all the backstory they want, and all the story reasons why you're supposed to be doing what you're doing they want, but it won't make boring gameplay fun.
Wiley.