IndigO2 is not bad. I saw Shalamar there a few weeks back, front row of the balcony (Jeffrey Daniel has still got it - never seen a human being move so effortlessly). Sound was pretty good. For that gig at least downstairs was standing and a free-for-all after queueing to get in. Seated ticket holders go in through a different door, up a lift, have a VIP lounge with bar etc. All very posh. Although it was possible to do a hand puppet show when the spotlight moved across where we were sitting (Mrs S put me in a handlock to prevent it after the first time) (What a rebel, eh?) Surprisingly intimate, maybe. Having said that I prefer the main O2 Arena and Brooklyn Bowl, though.
I wonder how the Bluesfest thing will move to the O2, though? I had a stroller ticket for last year at RAH and wandered about ad lib to see smaller bands (I say smaller - Matt Schofield was one). Not sure if this is going to happen or if it is just a few bands on the main stages?