Thanks for reminding me about the loctite. I forgot, and checked my screws, and one was loose. I just Loctited them.I have the Vltor with a CTR and really like it. Very solid (remember to loctite the two mounting screws, ask me how I know), very comfortable cheekweld that is in the correct vertical position (not too high or low). Installation takes 3 mins. My CTR does not lock up super solid in the closest to the receiver position. But even in the second position the LOP is shorter than a Warsaw length stock (don't have it in front of me or I would give you a measurement).
I have no experience with other stock adapters so can't compare it. Just know that pretty much any of these designs are going to add some weight. It is not as noticeable since it is at the rear. The extra weight tends to improve the balance of the AK, but again it is a little extra weight.
My second favorite upgrade to AK's after a Ultimak tube with a micro dot.