I have/had them all. I was about to buy another Demi but saw that it has the disk and I balked.
It is an amazing dish. The Demi is the best modifier for a one light set up, unless you have a Briese Focus 77.
Thanks for the info. i think i'll go ahead and get it without the opal and see if there is a difference.
I have a Demi and a Seti, what I notice with the Alu perforated disk is that it takes out part of the light in the center. More so than the Opal glass, not sure if I see a real big difference besides the catchlight being a little different. I never took the time to investigate the differences really extensive.
I do find I use the Demi more often than the Seti.