If you can afford the SU 2.0, you should probably take a look at the 7.3 FX; IMO it's a little nicer than the 7000 or Cadent - I think that the Deore derailleur on the 7.3 is a (small) step above the Alivio derailleur on the other bikes, and I don't think that disc brakes are useful or desirable given what you need the bike for.

I also think that you will be better off with the 32mm tires on the 7.3 than the mountain bike tires on the SU 2.0.