For a commute of only a few miles/Km, and if you don't want to get "sweaty", you could wear your regular work clothes and walk the bike uphill.
I don't like the new little "motorbikes" we have here in the states(a current "fad", for kids and folks with too much money), and I assume you would use a similar engine-they are incredibley noisy(my gosh and annoyingly so). Here, the law applies to the size of the engine used-above a certain cc(?49) it's a motorcycle. I'd be a bit hesitant to use the statement "if the current legislation were changed, far more people would use bicycles..."-can't recall the last time I saw a moped commuter(again in the states).
What's a stone equivalent to?