I moved my Launchbox from one drive to another with no problems, my emulators and roms did not move at a.KGen was Steve Snake's original attempt at a Genesis emulator, written because at the time the only existing emulator, Genem, ran slowly and had poor sound quality. If you have your roms and emulators outside of Launchbox and and the emulator and rom locations aren't actually changing then it will be fine. If you have everything contained within a single folder like having your emulators and roms in your Launchbox folder. Moving over your setup is easy enough depending on how you have everything organized. Retroarch has some very real benefits over stand alone emulators such as lower input lag, easy to configure controls, consistent visuals when using shaders and amazing audio syncing.

You can use the Retroarch UI while running a game to manage save states easily with your controller and once it's setup you rarely have to use the UI. Retroarch could be considered running a frontend within a frontend but that is a very narrow view of it.

Of course if you need help we're here to help out. If you aren't used to it I suggest reading my guide here: For the NES though there is an argument that can be made for puNES and Mesen. Retroarch has a bit of a learning curve but in all honesty for 8, 16 and 32 bit consoles it extremely good and in most cases the best emulator for those systems. Yeah, Fusion runs fine in previous versions of Windows but 10 has problems and hasn't been updated in quite a while.

Fusion 3.64 sega emulator