The cabrinha impact waist

What are they like? - v.comfortable, great mid back support
Do they ride up? - if they fit properly you should be right, but I find that when I just wear a rashie the lack of 2mm all round (from the wetsuit) makes a big difference, and it tends to ride up when overpowered. (a couple of homemade velcro inserts should fix this?). If your >6' tall the spreader bar will sit up just below the rib cage, but there is excellent padding and you don't feel a thing. As long as your happy with the bar that high!
Are they worth it? - probably not, the stitching is crap and will part under the arm area and under the zip, but I reckon I would have broken a rib or 2 without it.
Do they restrict arms? - Not at all
Are they too bulky? - you wouldn't know your wearing it
Are they a floatation device? not noticeable

sambo