Now that the engine on my '77 Motobecane 50L has been replaced and rebuilt, and all the bugs have now been worked out, I can honestly say that it is one of the smoothest, fastest, and most solid mopeds that I have ever ridden. I own a '76 Snark and a '94 Tomos, both of which are solid performers, but there's just something about the Motobecane that sets it apart. There have been times that I wanted to take a sledge hammer to my Motobeane, but now I'm glad that rational thought prevailed during those times.
In short, when a Motobecane runs good, it runs real good. But when it runs bad, which it often will, it is a major pain in the rear. I think that Italian mopeds are solid performers and require much less maintenance than french mopeds, but the performance of a Motobecane is clearly superior to that of my Italian mopeds.
Just my $.02 after a weekend of riding all three of them.