Don't overlook that a parallel twin is cheaper to build. The can have better traction, theoretically, as the power pulses are spaced in a way that promotes tire bite. But I doubt if too many here are good enough riders to actually use that advantage! They can package tighter, with a lower center of gravity. BUT...there is a cost with the design that I don't think outweighs the benefits. They buzz. They are not lighter, and may be heavier, due to the must have addition of balance shaft(s) to control some of the vibrations. They can make good power, or not, depending on the setup. Because the advantage of the ability to tip the cylinders both rather forward ( for more weight on the front ) that compromises the angle of airflow into the cylinder head in some cases. Most are tuned more toward torque than peak power, in part due to this problem with them. They don't sound all that good, if that matters at all.
One big reason I would buy a DL 1050 right now over an Africa Twin or a Super Tenere is the 90 degree v twin is smoother and sounds better. In the 650 - 800 class I can see the parallel twin being a good engine, but again you will give up smoothness on the highway. Not a factor in off pavement. But I would hate to see the 650 V Strom go this route. I have a Super Tenere in the family. The parallel twin in that bike has done nothing to make me like that engine design.
