To add a bit more I think the intention is to keep it either completely seated or have the first few rows removable to create a standing space but that would depend on money and you'd probably have to raise the stage a bit too.

As far as impact on The Musician goes there's obviously some overlap but more in terms of customers budgets I think. The Phoenix is about 260 all seated so you can both attract a different crowd and put on things that wouldn't really work at the Musician. What sort of music? I don't think anything is ruled out, whatever works in the venue and people are prepared to do, hence my eying it up for a gig or two.