Shiv,
If you are including me in that camp, I don't use it...I couldn't figure it out. Jamie might, I'm not sure. Chris Brauner said he does not.
I would suggest that we are more interested in this thread because it hits closer to home. I'll probably play 40 rounds of golf all year this year...25 or 30 of them will be in official competition. I'm interested in the rules, not just their application, but the logic behind them as well...
I do line up the ball with the ProV1X markings, or a line. I've used this method for quite a long time. Before the companies got clever and started placing the marks on the balls, I used to just use the Titleist logo. 99.9% of the time, I never remark the ball to adjust it once I've placed it down. When I get over the putt and see it a little different, I just move the clubhead a bit. The ball doesn't have to be lined up perfectly for me to go ahead and putt it.
Before this thread, I've never given the practice of aligning the ball on the green a second thought, and after 31 pages, I still don't.
It's just part of my routine, and I don't think it's wrong at all. I also don't think I've ever been thought of as a slow player either. Although I do think it is an easier way to align myself, if the rule was changed to ban this method, it really wouldn't be a big deal to me.