Fantastic watch, positive display is a delight, the added lume at 3/6/9 was much needed. Overall I'd say this watch is on par with the GM-B2100 but for less than half the cost due to the resin band!
The band is very comfortable, arguably an upgrade, compared to the standard resin GA-B2100 straps.
I only have a 6"~ wrist and this newer GBM-2100 strap fits me on the tightest hole (phew!) - whereas I use the 3rd tightest hole on a GA-B2100 strap.
The service from firstclasswatches was outstanding as always. I've used these guys lots!!!