One thing I'm wondering about the more I think about it is how Cake are going to manage Feature releases vs. bug fix releases...or if they're going to be mushed together. And, I reckon, is that going to mean there's a complicated user pool of folks who opted in/out at various times and have wildly different versions of the software. I'm guessing this has been thought out, but I wonder how it'll play out.
Also, the whole "you own it" at the end of your membership period, what if you need to do a reinstall? How do they keep all the different versioning intact? At least in the prior model you had your core point version and then any updates relevant to it. Now you'll have a whole range of possible updates available.