I've asked this question before:

http://diy.stackexchange.com/questions/3666/vented-vs-unvented-crawl-space

However, now that I'm going to get air conditioning the question comes back again and again people seem to have different opinions.

I'm the DC area where the summers are hot and humid.

I've got 2" rigid foam insulation on the perimeter walls of my crawl space and an interior perimeter drain system covered with gravel.  I'm going to cover the dirt with 2 layers of 6 mil plastic.

Now, I've got a few bids for AC and the AC guys have different opinions on the question of conditioning the crawl space.  The guy that I may end up going with thinks that I should vent the crawl space in the summer and isolate it from the basement (my space underneath is divided: 1/2 crawlspace 1/2 basement).  

However, there's this article:

http://www.buildingscience.com/documents/reports/rr-0401-conditioned-crawl-space-construction-performance-and-codes/?topic=/doctypes/researchreport

that talks against the idea.  My bidders think it's OK to condition it (small register + return at the opposite end).  

FWIW, I may also add a radon exhaust fan hooked into my french drain.

Given all the above info and your experience, what decision would you make if you were in my shoes?