There's a lot to be said for the power to weight ratio and you're correct about the available torque/HP numbers being factored in. Please keep in mind that HP numbers can be somewhat misleading. I refer to HP numbers for convenience as well as an indicator of "power" in general terms. But the real numbers that matter are the amount of available torque being delivered to the real wheel(s). For example, there might be 2 different bikes rated at the same HP number, but one might provide more available torque than the other and that's where the rubber meets the road.
If you crunch the numbers between the 2 engines that you're considering, you might compare the manufacturer's specs regarding Weight, Available Torque and MPG. You might find some trade-offs such as one engine weighing more, but offering more torque than the lighter engine. Or one engine offering less MPG than the other, but more available torque.
If the numbers were relatively close, I'd opt for more torque and learn to live with the MPG. Just my .02..........