I would spend more time thinking about what you really use the space for and if there's anything you'd change if you could.
We don't get too many chances to make a big change like you're doing and if you're like most people, once you have something for a week you find at least something you'd rather be different. ;) Hopefully this is your case too.
Personally, I'd sell the existing sump and replace it with a 40 Breeder, or if you want something with more space and don't mind the extra height, a 75 gallon or 125 gallon (if it'll fit your stand). Plenty of room to do whatever you want! :)
I love an open sump and can't stand the space-waste of a baffle. ;)