is a big difference in # of hours per stage OK though?

[CatMan]

For AM6, I did about 520 hours for stages 1-2-3. I felt I could easily handle it, so I increased to no more than 600 hours for stages 4-5-6. They were close enough to be okay to me, and it helped build a better foundation for my SM3 run. And 600 is getting close to the 672 hour max limit per stage anyway.

Hope that helps you. I'd say a bit of an increase is okay, but try to keep it as balanced as possible as each stage plays on the preceding ones.