In my quest for a ring flash, I opted for the Orbis. With the Orbis, you're able to incorporate mostly all different flash head sizes, 430, 580, SB's etc. It doesn't have a bend on the attachment itself to accommodate a flash on-camera. It has a straight channel (better I think in it's distribution/spread of light, in fact pretty even from top to bottom) so you can only use it with the flash attached via a Hot Shoe Cord or wireless trigger and hand hold the set-up to your lens. That might be a deal breaker for some, but as mentioned above, I believe it has better distribution of light, and it's even more useful because you're not limited to using it on axis only...it produces beautiful light off axis as well.
If you think a ring flash is going to be useful in your arsenal of light modifiers, I highly suggest you consider the Orbis, especially if you intend to spend a good amount of money. Better in so many ways over the Rayflash, imo.