I like Adam Back's 2-4-8 proposal better, as it provides a gradual transition. Note that Bitfury's support for BIP 100 was based on their assessment that increasing the limit to 8MB right now is too fast. Mark Friedenbach has also warned that while 8MB is likely safe with current networking hardware, it hasn't been sufficiently tested.

I wouldn't mind accelerating Adam's schedule so that 8MB is reached in 3 years, not 6.