I'm aware of Tegmark's ideas, although I haven't thought about them much. I was not aware that they have a following on this site, probably because I haven't read much of the decision theory material on here. I'll read up on the idea and think about it more. My immediate uninformed inclination is skepticism, mainly on the grounds that I doubt the anthropics will work out in Tegmark's favor without some gerrymandering of the ensemble. Also, being able to conceive of a mathematical structure as an independently existing entity rather than a formal description of the structure of some material system seems to require a Gestalt switch that I haven't yet been able to attain.