What kind of touring?
Day rides?
Week long?
End to end?
My own
personal taste would not include an aluminium frame bike for long comfortable rides. Especially with an Ali' fork.
Others will disagree but my own experiance is aluminium can give a harsh ride. On the other hand a stiff frame helps to transmit the power,
I would also consider drop handle bars especially if you end up riding into a strong headwind. Flat bars limit your hand positions so fit bar ends at least as well.
Mudguards are not essential but well worth it again for comfort. (dry bum & feet) The marin will take these by the looks of it.
The gear ratio of the marin would be O.K for not too hilly rides. The chainrings and rear cassette can be changed if needed to give lower ratios.