Is this a critical, production level application or a small one-off? Can you deal with the extra time that the learning curve of MVC will take or do you need to have it done right-away? Can you afford to scrap the whole thing and start over if MVC doesn’t work out? Are you willing to have the platform change (probably not much now that it’s in beta) while you are developing? Is there another project that is less critical that you could use MVC on to learn it.
Depending on how you answer these questions, learning MVC on this project might be worth it. Personally, I think it is a better architecture, but a less mature technology at this point. It has certainly increased the testability of my web code. I expect to move all of my development in this direction over the next year or so, though I doubt if I will change gears in any of the projects that I have had under development for awhile. I’ve just started my first new project in MVC. I wasn’t willing to commit to it until it went into beta and I think that it will be in production before I’m finished with the project.