Well if you try to sell your CA MP5a4 Tactical Lighted you wont get much for it, MP5's have the worst resale value. P90's are great guns in many aspects. Like weight, stong gearbox, good hop-up's ect. Problem is you will have to have someone make you custom mag pouches for your loadout like Dave. You have to ask yourself why are you changing form one to another? If its just because you think one will shoot harder than another. Than you are a Dork, and should shoot yourself with it. If its becaue you like the feel, weight, the capablity for accesories, and have a plan on how you want your P90 to perform. Than I say get the P90. I could tell you the best ways to get a P90 up and running. It will be one hell of a project gun.