Anyone got/used one of these ring flash adaptors?

EDIT: OOPS I just found a similar thread, sorry. (maybe this could be an update thread...)

This is a good angle of it but there are different ones for different models because of the size:
http://www.warehouseex​press.com …/default.aspx?s​ku=1026198

I'd like to get one for use with a 40D and Sigma EF500 DG Super (looking further there doesn't seem to be a Sigma version :mad
I'd use for the usual modelling and macro. I like it because of the wide diameter so I could even use my 100-400.
Anyone used that combination? Thoughts...?

i don't have one but it seems like a great alternative to the standard options on the market... hopefully somebody on here can shed some light on this products effectiveness (excuse the pun)

Here is the actual product web site:

https://www.expodisc.c​om …h:_The_Ring_Fla​sh_Adapter

very interesting

David Hobby's been having a great time with it over at Strobist. I also know a local photographer who's gotten one, and says that he loves it. I'm hoping to go shooting with him sometime in the next couple months, so I'll get some hands-on time with it...