Harry,

I'd highly encourage you to look at the abstracts being presented at the AAN 2009 Meeting next week. There will be a lot of data presented on patients pre and post Tysabri (Relapse rate, EDSS, QOL measures) that may alter your efficacy perception relative to the CRABs. You might also want to recheck your info on CRAB costs as their prices hacve crept up to within 10 to 15 of Tysabri's costs.

Chris