I shoot groups of people for a high key look, through a 54x72" softbox as the main light. I get f/5.6 ... f/8 now depending on how far I have to position the softbox to cover the group. I sometimes use a 1/2 stop less opaque optional front diffusion screen in my softbox, sacrificing some of the light quality to get to use a smaller aperture.
I would like to be able to use f/11 in most cases and with the standard front screen on my softbox. 1300 watt-seconds will get me that. I've been looking at Elinchrom Style RX 1200 monolight
http://www.elinchrom.com/products.php?p_id=49#content but when I came across Paul C. Buff's pages on Einstein and the digital triggers, and the forum, it appealed to me how he went about his business and how upfront he was with customers. So I'd give him my business if he delivers. I could get the digitriggers and 640 watt-sec now that I could later use for a second light - as long as I know there is going to be a 1200/1300 watt-sec option that has the same technology level as the Einstein. Otherwise I'll have to go with Elinchrom - to me they are an impersonal European corporation that charges quite a bit more, but they deliver similar features and they have the stuff available - simple as that.
Michelle