I've got a 2013 Trek 8.4 DS, comparing the specs to a 2015 Roam 1 and looking at the savings ($80) I would get the Giant over the Trek assuming when you ride them they feel the same.
Upgrades of the Giant over the Trek
- 30 speed vs 27 speed
- Full Deore Group vs mix of Alivio/Deore Group
- Shimano vs Tektro Brakes
- $80 difference on MSRP
Ultimately, whichever bike feels better when you demo ride should be the one you choose. While the specs and the ~10% difference in price makes me lean more towards the Giant, the bike with the most comfortable geometry is the one you should choose. That one extra "granny" gear while climbing would be a godsend for me as my cardio is quite lacking.
I am leaning towards the giant bikes. It has been hard to get around to try all of these different bikes. Regarding the 2015 roam 1 vs 2014 roam 0. I looked into the different forks and found that the 2014 has hydraulic dampening, a rebound cartridge and a 30mm stanchion tube diameter while the 2015 doesn't have these features and has a 28mm stanchion tube diameter. Do these things matter for a beginner rider? I haven't been able to test ride the roam 1 because it is so new but the roam 0 feels great.