2c: I never worried about migration-- GAE is so much simpler than other systems, unless you went crazy with the datastore, most issues are a few hours to port.

2c: I never worried about migration-- GAE is so much simpler than other systems, unless you went crazy with the datastore, most issues are a few hours to port. In addition, TyphoonAE has a reasonable reputation and is very active. That all said, porting scaled-up apps is never fun-- the above only applies to smaller apps.