For me it is the highway top end speed that would be the limiting factor.
I had the same issue with my Honda CBX 250, that without a sprocket change, was limited to 110 km/hr on highways while the rest of the traffic were at the 120 km/hr speed limit.
Some other 250cc road bikes like the Kawaski could reach 140 km/hr plus. I do understand the barn door effect / drag on the taller bikes, but with modern technology I expected more from the DL250.