Patrick,
Another possible anti-yip method if you have to go back to a conventional putter is the two-thumb grip; the thumbs are side by side on the top of the grip, and you press hard against the grip with the lifelines of each palm. You have to install a particular type of grip on your putter; there are several on the market that are either designed specifially for that grip or are workable with it.
I've used the two-thumb grip for several years now, and it essentially eliminates not the yip itself, but the bad result. I still yip on the 2-3 footers from time to time, but the ball goes straight.
I've used the claw/saw and overall I prefer the two-thumb, but it's a close call. The two-thumb is a little easier for lag putting and is a little better anti-yip; the claw/saw is probably a bit better at getting the ball on line. The belly putter never did a thing for my yips, though I think it did help my conventional stroke quite a bit. I've never tried the long putter, and I guess now I'm glad I haven't gotten attached. As to the face-on method, I may fiddle with that a bit over the wiinter; it makes too much sense not to.