The stuff running on the ARM itself is all open, but the firmware blob runs on a separate CPU with a different instruction set, which has a view of the entire m

The stuff running on the ARM itself is all open, but the firmware blob runs on a separate CPU with a different instruction set, which has a view of the entire memory map of the device and ultimate control over the device's behavior (sound familiar?). I may be wrong, but my impression is that a lot of the other ARM boards out there have the ARM chip as the main CPU, and without a management chip watching it. In any case, a board like that, or a Pi with a reverse-engineered firmware blob (currently in development) would be better than the Raspberry Pi as it is now.