I think maintenance is the key issue here, or with any car. My last speedster (Vintage) was driven regularly and after 3 years showed no signs of frame fatigue, body cracking or engine problems. It was a factory built 1776 single carb from Vintage. In fact the only thing that did show, was small paint chips from rocks etc, other than that it looked new. That being said, I never skipped even the most minor maintenance, oil change/valve adjustment every 3months - 3000 miles. Garage storage, wax every 2 months, etc. Just beware of used speedsters that were built by less than reputable manufacturers (Ryan Motors) or home builders. While there are some home builders here that probably have better than factory quality cars, there are some who just slapped the car together with glue and spit.
Good maintenance applies to any car regardless on the manufacturer. It goes a long way in keeping you from the dreaded tow truck call. My inlaws constantly want to buy my old cars because they think they never break down. When they buy a new car, it will be on the side of the road in less than a year. Of course they spend NO money on maintenance. Bangs, knocks, warning lights, low tire tread, all get ignored until the car just quits. Then they spend huge amounts of money to fix the problem.
-=theron