I just bought a #7 (the one with the fangs) a couple days ago.
It's like magic!
Well, ok, not magic, but it is a huge improvement over my old putter (a cheap Dunlop mallet).

I had visited the golf shop 3 or 4 times and tried out pretty much every model they had. None of them were as easy for me to line up and as easy to hit straight as the #7. I was initially thinking I'd get a 2 ball putter because I had heard a lot of good things about them, but the #7 felt much better to me. Something about the balance and the shape just makes it super easy to hit. As a bonus, the #7 is one of the least expensive of the XG series. $119.

I played 27 holes with it yesterday and it definitely saved me a bunch of strokes. I used to miss 3 footers quite often and I was maybe 50/50 from 5 feet. With this new putter, I can't seem to miss anything inside of 6 ft. And I made a bunch of longer putts, including an 8 footer for birdie and one from about 12 ft to save par on the 18th hole.