Well, this sounds familiar.
The previous owner had installed the SBC brackets before I bought the VX. The passenger side works perfectly but the driver's side would still twist forward while being raised. Silicone spray made it work great for about a month, and a second application helped when it needed again later, but was the result was not nearly as good. A few weeks ago I took the window out while replacing the lock assembly.
When I reinstalled the window, the twisting was the worst ever until I slid the SBC bracket as far toward the door hinges as possible. No more twisting, but now I get a little wind noise on the highway. There is also a worrying "thunk" as the window completely closes that makes me think the top of the window is not aligned properly with the upper channel. Seems to be a fine balancing act.
I would have kept trying to find the sweet spot, but there is so much slop throughout the entire regulator assembly that I was left with the impression that it is just plain ol' worn out. (Lots of speculation on my part since this is the first time I ever played with "door guts.") Once I have time to mess around with it again, I intend on comparing it to the passenger side regulator before I actually start shopping for a replacement.