The size of the market was discussed by others. It is potentially very large. However, is this drug a major breakthrough? Probably not. I own BIIB so I just look at this as a bonus. I'm really in it for the MS results. BIIB is also in Phase III with Rituxin for RA. Hoping for good news there as well. Since you are in ELN, I would focus on the huge potential in MS and just consider anything from Crohns a bonus. They've begun Phase II with Antegren for RA with more diseases to follow at some point. I'm really expecting Antegren to be huge. Hope I'm not disappointed.
I chose BIIB over ELN for a large investment simply because I prefer the bigger safer company with more potential add-ons.