I have a Jimmy Lewis 11 X 30 for standup, and wrote a little review about it in my blog at http://www.ponohouse.com/ponoblog/?p=112. I think this a great board for beginners and geezers like me (just turned 60), I'm not so sure about more experienced surfers. I'm a relatively new surfer (about 4-5 years), I started surfing after I screwed up my shoulders too much to windsurf (tore my rotator cuffs playing rollerblade hockey). I think surfing helped get my shoulders back into shape enough to windsurf again--that and superfreak sails, which I consider to be Viagra for busted up old windsurfers.
For beginners, the 11 X 30 is magic. I've put people on it that have never tried standup before and they can immediately paddle out, even in the kind of chop we've had recently on the south shore here in Maui.
When you get in a wave the board feels wobbly, unless you shift your weight to either rail. I think it's just hunting a bit, and it doesn't really do anything weird, it just feels that way. Moving your weight makes it stop, and then it surfs like any other long board with a lot of rocker and round rails.
I also have one of Jimmy's 11' 7" standup boards that I use as a big surfboard. For a guy my size (6'3", 240 pounds) it's really great in small to mid sized waves. Paddles like a rocket, and it'll catch a ripple on a millpond. I've started using it for standup, but I need to get better for it to really work. Also have one of the Ding King's hollow standup boards. Very nice, wonderful performance. I've got a mast track on the ding king board, none on the other two. Wish I had, but I bought them finished. I'm not sure how well a mast track will work on a epoxy sandwich board.