I'm one of the Norco Belt Drive guys (IRClean is the other that I know of), though I've moved back from the great white north (good day, eh?)
I've sold mine, but used it daily of about 14-15 months, in SS and Alfine 8 speed configurations, and in all weather conditions.

I really liked it, but have gone back to a chain drive since my climate is essentially high desert (Utah, Colorado), and I see little benefit to the belt.
I guess I need to qualify that- in my view, much of the benefit of the belt drive is nearly zero drive train maintenance in crappy weather, which is REALLY nice. I could also see some benefit for super sandy/salty conditions. However, if you aren't riding in these conditions, the belt drive is more on par with a good chain drive, IMO, but requires higher tension than a chain drive, which raises some concern for bearing life, etc.

I was using the original (not centertrac) belt drive. The main diff that I am aware of is that the original belt system was far more sensitive to cog alignment than centertrac. It added perhaps 10-15 seconds to my wheel installation so I could fine tune the sliders to ensure that the rear axle was dead even across the dropouts (the belt would wander off of alignment if either side was too far forward/back). Once this was set, it worked great. Dead silent and really smooth for SS or IGH use. As mentioned above I found the belt drive system to require higher tension than a chain, in order to prevent the belt from slipping (popping one notch) under load (especially in the wet).



I'm not familiar with Stop cycles, but that frame looks like it would be fine. Another option would be the Van Dessel WTF, or perhaps one of the bikes from Spot (not Stop )

It sounds to me like single speed would work just fine for your use, and would support your goal to keep weight reasonable. That said, for commuting, weight shouldn't be too much of a concern IMO - you can have a really fun SS bike that is 20-24 pounds with racks and fenders.

Panniers - many (such as Arkel and Ortlieb) are super easy to get on and off the rack (once set up), and many have shoulder straps to make carrying easier.

A final thought - most chromoly frames can be converted to belt drive using the Paragon Machine Works stay splitter (which opens your options considerably).

It sounds like you have a fun project ahead of you!
Best of luck withwhatever you decide to do!