a smaller bike’ll be easier to learn on, especially if you’re a tad on the short side. the added power of a bigger bike would likely be offset by the extra amount of wrestling you’ll have to do to get it to do what you want it to do. what a speedometer goes up to doesn’t have a great deal of bearing for the most part, in my cage experience. my cargo van goes up to 120 on the speedo, I believe, but there’s no hope in hades that it’ll ever hit that speed. my old geo tracker’s speedo went to 90 and I got clocked (I was young and dumb) at 115, I’d maxed the speedo out and the car just kept speeding up. I can’t imagine a bike going that fast down the highway, the tracker was shaking like jello in an earthquake and it weighed more than anything short of a goldwing. most advice I’ve read that I’ve felt had any merit whatsoever generally advised against relying on speed to get yourself out of situations anyway. and 5 miles interstate isn’t much anyway, I’d say stick to a smaller bike that you can handle, something that you can maneuver nimbly and feel comfortable on will get you out of far more situations than raw power and speed will, and if not…well…you’re doing it wrong.