a 2ME switcher means that you can create and build your effects in the top ME buss, and then enter this entire build into the second ME buss, which is "downstream" of the first ME buss. Did you ever watch a sporting event or news show, with all kinds of junk on the screen ? Well, that's how they do it - a multi buss switcher, that can create multiple layers live. Bigger switchers from Grass Valley, Ross, Sony, Snell and Wilcox, etc. have 3 and 4 ME switchers, for the really complex stuff.
All the switchers that BMD makes have multiple program outputs - you can use the AUX outputs as additional Program outputs - or you can buy the Blackmagic Mini converter SDI Distributor to give you 8 additional HD-SDI outputs if you need them.
Now the BIG question, is - "why does anyone want all that crap on the screen anyway !". But that question is for a producer - it's our job to just give 'em what they want, and shut up.
bob zelin