Howdy RFP, welcome. A 4 stroke is not as loud as a 2 stroke and while not as "quick" my 50cc honda 4 stroke (stock, all) is faster then any of my stock "80cc" 2 strokes. Is a lot easier to refuel on the road with out mixing oil and is a more comfortable ride and vibrates a lot less. The down side is it is 3 times the cost. (I think well worth) But this is a hotly debated issue and you should read up on it. Here is a link to just one of the discussions on this very topic; http://motorbicycling.com/f31/2-stro...roke-7406.html
If you get a chance, ride both before making a choice. Please keep us updated. Good to meet ya.
Edit; I failed to mention my 4 stroke is a better hill climber, but it is the only 4 stroke I have owned. Not a really worrisome issue as with a motorized bicycle if the hill is winning, a lil peddling and your flying. Makes ya feel like superman doing 20 uphill on a bicycle, snork) Also a 4 stroke is more dependable.