No way I'd pay $400 for that. I have installed several of those kits on TJs....but not on a JK. I'm assuming that it's similar. On the TJ, there were some wiring plugs to add or remove a wire or two....not too difficult if you have some experience with wiring harnesses. There were also a couple of splices to do. The rest was just running wires or removing stuff to get down to the places you need to be. The manual that comes with the harness is like 20 pages with pictures...not many words. LOL
You can certainly use the top without ANY of that stuff hooked up. Just use it that way, study the manual and decide if and when you wanna attempt it. I seldom use any of that stuff, but I hate to not have it "completed".
That kit is probably a couple hundred bucks, so if you decide you don't really need it, you might can just not buy it...or maybe return it.