I just finished installing a Warrior tier PnP kit into what was a Warrior tier Disciple. Reason I made the switch is because I bought it in 6W (non-PnP) and it just wasn't bright enough compared to my ASP 12W+, now the troubles I had were mainly drilling out the old switch (because Saberforge glues them in) and trying to fit all of the wires into such a small hilt. Once the old stuff was out and I basically had an empty hilt everything slid in like a glove, except for the fact that the latching switch was almost too big for the hilt. you probably cant fit a piece of paper between the back of the hilt and the end of the switch and you'll have to glue the switch back in because the nut they give you would be a nightmare to try and get on. SO, once you get the switch glued in and everything snug now comes the fun part of trying to jam pack all of those wires that connect to the LED inside that tiny (and in the Disciples case, thin) space between the switch and where the LED needs to sit in order for the screw to hold the LED tight. It will take a good amount of time and headache but it will all fit. (I used a sharpie to push the LED down and tighten the screw at the same time.) All in all it took me a little over an hour to completely gut the saber and give it new parts. Hope this helps.
P.S. I have the champion PnP in my ASP, personally I am not a fan of it. the power up is fine but the clash is either too sensitive or not sensitive enough and the movement sound loops often. not anywhere near a real saber. not to mention when powering down you have to hold the switch for around five seconds before it starts to shut off. may not sound like a long time but trust me it is.
Good Luck with your install. Any questions feel free to message me