I'm in the process of getting bids, and one foam guy mentioned that he uses a "hybrid" foam, Icynene MD-R-200. I'm not familiar with this. Can someone enlighten me? He said the R-Value is less, but it is easier to spray, and cheaper.

MD-R-200 an Icynene version of 2lb foam. It's R value is significantly higher than open cell 0.5-0.7lb goods, but somewhat lower than industry-standard 2lb polyurethane or polyisocyanurate spray foams-( ~ R5 per inch vs. ~ R6-6.5 per inch.)

See: http://www.iapmoes.org/Documents/ER_0174.pdf