Had a discussion with my friend.

He recommended Norco, reasons:

- belt drive is much less dirty and esp. grease dirty (which never washes off)
- steel frame is nicer
- mechanic disc brakes are fairly easy to setup and and maintain, while retaining enough stopping power
- alfine 11 ought to be close to a drop out replacement for alfine 8 so all should work with it
- cable routing can be done internally later on, if needed
- check geometry closely with your individual body measurements, if you can't test (done)
- corrosion (use frame saver or similar for protection)

I'll go with Norco.

Thanks for all the replies.