Dave,
Paper looks interesting, particularly the use of free wake geometry in Camrad II. Interesting that tandems require similar power to coaxials - that may be one to watch.
The side-by-side configs will always apparently fair better because they increase the span of the lifting system. To compare apples with apples i think a constraint of the config should be to define the span then size the rotor accordingly - this defines the landing areas the machine can access. I suspect that coaxial starts to look better with this constraint.
At some point (after proj deadline in Sep) i would like to do a more basic comparison. I've now got a reasonable model for reverse flow, and am just starting to think about inflow effects (critical for counterrotating machines). Don't hold your breath just yet though!