I am one of those who like the Arkel attachment system. I don't have the commuter bag nor the carrying strap, so I can't comment on the other issues. I use my Arkels (most often the T42s, but also GT-54 and TT-84) on a Blackburn rack, two Bruce Gordon front Lowrider racks and two Burley Piccolo Moose racks.
A few suggestions:
- Bottom hook vs rack.
I have bent my fender stays so I have more clearance around the area where the bottom hook goes. On the right, I use a twist tie to attach the derailleur cable housing near the quick release. That way, I get more predictable shifting because the cable always remain in the same place, and I never hook the pannier "though" the derailleur cable.
Thoughout the years, some bottom hooks are slightly more open than others. I can't tell you which works best.
- Shoulder strap.
Would it work if you kept it onto the pannier and inserted it into the bag?