Ring Lite Vs. Twin Lite

Im considering purchasing one of the two of these, and wanted some suggestions. I love macro photogrphy, and i plan to do most than life size photos. Right now im just using tube extensions, but i want to purchase the 100mm macro 2.8 shortly...i appreciate your suggestions.

Twin light is more versatile .. almost infinitely so.
Ring lite offers a very specific look with some variation that can be had by using one or both sides of the ring.

If I had only one I'd go twin light all the way.

is the some tutorials i could read to get a better idea of how versatile the twin lite is? Perhaps examples of either light so i can see what my options are?

I have the Sigmas ringlite and I'm more than happy with it, it is adjustable though it does give a certain look to images taken using it, but I like the look of them, some of my work can be seen in the macro thread, I'm only leaning so the quality isn't the best

Cheers

Alan