Hmmm, I can't get through to FNP either right now...
You mention
PremiumNetPass and ProAdult, but in your first message you said you were leaning towards a cheap/free AVS. Not sure about ProAdult, but with PNP, you need at least 300 pictures, so I don't know if that's what you were wanting!
Also with Gold/Platinum level sites, if you were thinking of going that route, usually have to be exclusive, although PNP openly accepts doorways, which could potentially get webmasters in trouble with the other AVS's.
I'll take a look for an example of a multi AVS site. Personally I always go exclusive, but I like the idea of doing a multiple AVS site, except that you make less for non-excluvise sites
Bruce