I would like to know how the 40 w extension tubes went. I have the 25 and 12mm canon tubes and i am considering the shorty 40 with tube for ring macros at weddings. ...
Please oh please someone bring somethin to the table.
Well, Bosman, since you asked so nicely...

I grabbed a shot with the 1D X, Extension Tube EF 25 II, and EF 40mm f/2.8 'pancake'. My wife's sparkly diamond marquis with smaller marquis sapphires surrounding it is on her finger, and she's asleep, so you'll have to make due with my wedding band. It's not unblemished and new like the ones you'll be shooting, since it's been on my finger for a few months shy of 20 years. But there are only two wedding rings in the house, so this is what you're getting...

Two shots, first is the full frame, uncropped image reduced to 800 pixles wide, second is an 800 pixel wide 100% crop. Shot at 1/40 s, f/11, ISO 400. Straight conversion with DPP, only adjustment was to the WB (I cooled it off a little - I should know better than to shoot tungsten light on a red throw pillow with AWB, the original looked a little Tolkien-esque, One Ring To Rule Them All...).
In terms of dimensions, the band measures 7/8" diameter. The shot was at the MFD of the lens, and the working distance (front element to wedding ring) was ~2.25".
Hope that helps...