I've done fairly long journeys on motorways (100 miles ish) on my old aprilia rs250 not on my nsr250 yet. It did the miles ok but felt like hard work holding the speed constant found i kept having to change gears what felt like a hell of a lot. I would rather get off the motorway and do the twisty bits as strokers like those roads more.
Suppose i'd do it if no other way but not what i would consider fun.