I'd do dual phase,because YOU WANT ONE,and there's not a big price difference.
I bet 300-400 dollars an electrician could fix you up with materials+labour,( batteries not inc 
)..
It probably depends on where the electrical box is in relation to the receptacle. When the house was going up (12 yrs. ago) I had them put a single receptacle on its own circuit in addition to what was on the wall where the system was going. They did use a 20 amp breaker but just 14 gauge wire (I didn't specify - obviously I would do it differently today). I finished the basement about 4 years back (have another system down there) and where the wall is to the main room upstairs it is now finished basement. It would probably cost me more than 300-400 dollars to have someone rip up and repair what is finished just to have the electrical work done.
I just ordered a 20 amp Torus last week (I'll use my other power conditioners in the bedroom and basement systems). It will be fine for my 14BSST, my SP 1.7, and source components (e.g. BCD-1, Blu-Ray player) as they will only be one one at a time. If I had done things differently, I would have at least put another receptacle on its own circuit. I'll suffer with the 6BSST (used on the center and surrounds) and my 4 main system subs plugged into the wall. If I had things to do all over, I probably would only have a 2-channel main system and I would have done the basement in a different configuration.
In my old house, I had a duplex receptacle on its own circuit but it was much easier as the main system wall where the receptacle had the garage where the electrical box was located. Adding additional electrical stuff in that situation was much easier. Ripping up the unfinished sheetrock in the garage and repairing it would be really easy in that scenaio. Before I finished the basement I ran component and video cables from one side of the main room (now buried in the basement ceiling) to the other and chopped up a column behind to the listening chair to get the cabling up high for the projector. Took me a mild bit of creative thinking to hide the long HDMI cable I ran last summer for the new projector. While I don't plan to move again, if I ever do, I'll try to do a better job of leaving more options open.
