The only downside of doing a sump is that if the tank doesn't have a overflow box it can become a PITA. You need to get a overflow box that does not loose siphon. There are some boxes out there that hang on the side of the tank that any time the power goes out or you shut the pump off to do a waterchange the overflow box looses siphon. Usually it seems that the power goes out when you are out of the state on vacation.... so you come home to a dead pump & dead fish
Get a overflow box that is designed to not loose siphon & you are fine. Power goes out & overflow box starts working when the water gets high enough.
Also, if you are doing FO you could also sell your LR. It's not needed on a FO tank & allows you to add chemicals directly to the tank if they get sick for some reason & you do not have a QT tank. I was going to go the FO with LR route but Joel talked me out of it.... saved me a boatload of money to!! A good wet/dry is all that's needed..... a good skimmer does help but isn't a necessity. I have always used w/d filters on my tanks..... & sometimes with a skimmer.