So far I am very pleased with the bike. Yep, it is a little heavier than I would like, but you do not notice it as much when the bike is under way. The bike is very flickable, and the engine more than makes up for it. There is a shop in Mass. called Bikeworx that does a lot of work on these bikes, and has been able to get over 70 hp out of the MZ engines. From what I hear, these engines are realiable and amazingly fast. My opinion is that if you are going to wrap a frame around that much horsepower, you may as well make it as sturdy as possible.
As I do more mods to the bike I will look for ways to lighten in. Getting rid of the stock exhaust and emissions canister helped quite a bit (about 10 pounds) and I am sure there are other things I could do to help. I'll keep you posted.