Yes, the rear suspension is adjustable. But the point here is previously I had a 2010 model Honda CD 100 which also came with adjustable rear shock absorbers, but they never required any adjustment even with 3 people on it I kept them in their stock adjustment for the two-and-a-half years I used it. So why I should bother changing suspension adjustment in GD? It should perform well in the factory configuration. Factory configurations are well-suited for normal operation of a machine; a motor bike is designed to carry two people: driver and passenger, and I do not think riding GD with a pillion rider is taking it beyond its normal operating conditions. So its rear suspesion is indeed more softer than it should have been.
Mileage, it's improving with time. The first mileage I got was 45 km/L, the next one 49 km/L and probably tonight I'll have the third reading as my bike entered reserve mode while coming to office this morning. It is going good. I have not seen any 125cc engine going beyond 45+ km/L in this department. Furthermore, I am going for its first tuning tomorrow Insha Allah, so I am hoping for a further improvement in its fuel consumption.
Plus, I have no doubt about it being durable from the quality of components used in its manufacturing. However, only time will tell.