Swapping a sound setup to another saber is pretty dang easy, to be honest. You don't have to mess with soldering the board, switch or LED at all to be honest. Of course, take out your batteries before snipping and soldering anything, but I'd imagine you already knew that. Afterwards, remove your switch. Your wires should have plenty of play to them, especially if you've got the pack at least partially into the saber. (don't put it in fully without batteries, they're a pain to get back out) Get plenty of the wire out and snip the wires on down a bit, to where you can just strip them and solder them back together. Afterwards, pull out the pack fully and snip the wires coming out of the buck puck. If you have flash on clash, there will also be a wire leading to the FoC negative from the board. Snip that too. All of those snips should also be done "out in space" a bit so that you can just strip and sold the wires. After you snip those wires, everything will come right out. Doing that will save you from having to do any soldering to the board, LED and switch. Reassembly is simple after that. Just strip and re-solder wires. Though, as those hilts are different lengths, you may want to have some extra wire on hand and you will, of course, need heat shrink.
Alternately, you can also snip the switch wires down by the board too, it's doer's choice.
The only thing you have to worry about is if the stunt Reaper has the same kind of switch as the saber that it's getting the sound board from. If so, you can just swap the switches when you do the electronics switch. The stunts use a latching switch, which goes down and "clicks" and stays down until you hit it again. The sound sabers have a momentary switch, which doesn't stay down and springs back up. This type of switch is necessary to how the boards function. If they have the same style of switch, (guarded or AV) it won't be an issue. If they don't, you may need to pick up some new switches, but that's not an issue.
