Agar roojka 5-10km se jyada commute nai hoga toh Rc lelo par agar tumhara daily commute 10km se uppar h toh RC pe you'll start developing back problems..
Because D400 is a cruising centric motorcycle , you can barely use in city as it gives a mileage around 20-22 kmpl in city while duke 250 is an all rounder as you can commute and go for a ride. Bigger is always not better if you see in a practical way. Dominar is a hyper(cruiser) while Duke is a good commuter as well as a good ride partner.
