In terms of upgrades/modification, X series lights are a disaster.
If you want to do more than replace a twisty with a clicky, sell it and get a 6P.
I'm not sure I agree with your use of the word "disaster", even when phrased "in terms of upgrades/modifications" because it implies that the lights are no good. In reality, they are very good lights.
Perhaps it would be best to say that they are difficult to upgrade, something best attempted by a modder as opposed to the average flashlight user. In this regard, they are no different than the majority of lights sold by other manufacturers. We're just spoiled by the old drop-in style lights.
I hope I don't sound too harsh, I love my Malkoffs. I bought a couple of hundred dollars worth of G series parts from you this month, and I put some more stuff in the basket today...
To jmiro: :welcome:
ElectronGuru's right, get yourself a bored 6P and get ready for the ride of your life! (And also kiss your wallet goodbye!)