Go for it, if you have a backup of everything. Although OSX isn't as bad with bit rot as Windows, it can get somewhat sluggish after a while.
It's almost always a good idea to do a fresh install and rebuild if you're going to wipe your computer (rather than restoring from a backup). Whatever is causing the problem could come along with the backup restoration into your new setup, particularly if your data has been transferred around from machine to machine for a while without ever being rebuilt.
As for cons... obviously it's going to take you some time to get your system rebuilt. There's also the possibility you're going to lose some license keys that you no longer have on paper somewhere. Or that you could lose some other data somehow.
A bit of advice: Make sure you have two backups before you start; your normal one, and a full image of the machine taken immediately before you wipe it. Don't be sloppy about it. My wife just sold her old machine and bought a new one. Neither of us realized that her Time Machine drive had gone flaky (since she's never had to use it). Had I not taken an image of her old machine first, she would have lost everything. Two is One. One is NONE.