I'd love to go to one or both of the London Epic events in May. However I don't have an army that I can really use in any sort of event setting (my 'current' Epic army is my old Space Marine era army, consisting of a battered pair of Warhounds, a Space Wolf Great Company, two 'flying brick' Thunderhawks and a few other bits and bobs), nor have I even played an intro game of EA as of yet. Believe me when I say that sorting out an army and getting some games in is definately on my 'to-do list'. Unfortunately finishing my WM and WMA armies, and getting 1.5-2k painted for WH and 40K are higher priorities, the later two because I want to be able to play games, and if the only game I can get one week is WH or 40K its better than playing nothing...
As to SG event uptakes, poor turnouts are a result of a lack of interest from GW as much as anything else. Ultimately the numbers of people that play our beloved games tends towards contraction rather than expansion, simply because its not being pushed in the stores or properly supported. And whilst there are obviously die-hard fans like ourselves that will go to whatever they can, they can be taken out of the event scene as I have pretty much for the last four years or so for various reasons.
So anyway, yes to ensure that a SG related event can actually go ahead really you need the likes of WH or 40K 'to make up the numbers' so to speak. I'm surprised about the lack of BB takeup though, I'd always thought that it was the one SG that was the exception in that regard?