To be honest, I've never been in favour of the 'two room' thinking... and here's why!
I honestly believe that a Soul Music promoter who want's to run a night and get his or her point (or aspirations) over should be aiming to do it in one room (whether that be Oldies, 60's, 70's, Modern, Crossover or whatever!).
Anything else always seems to me to be an attempt to paper the walls, or up the gate, to my way of thinking.
When myself and Tats Taylor, Kev Briscoe and John Benson set up the 'PITCHES' thing (over 10 years ago) our intention was to promote quality Soul Music from ALL four decades all in the one room... hence the first 'Across The Board' Soul night and the coining of the phrase.
Whether anyone else would subscribe to it or support it was untried and untested at the time. Fortunately it was hugely succesful... over several years... and started a continuing trend, but at the time, whether it had worked or not, we were just doing what we passionately believed in.
Thus, if your thing is Northern Oldies or Modern Soul (or whatever the genre) and you honestly believe that that's what you want to promote then go all out to make that one room work, rather than dilute the crowd (and the message) and compromise your intentions.
Personally, I'm still of the opinion that a 'truly' Across The Board' / 'Just Soul' approach works best for me (as we see at Soul Essence) where Soul Lovers can appreciate and experience the best of everything that Black America has produced over the past 40+ years.
Sean