In recent years, 3W has had some problems with porous castings. Also, they have designed a minimum amount of metal in the case to keep 'em light. The combination of porous castings and thin metal some times leads to leaky cases. The latest 3W engines have better looking castings, so I think they got the message.

A buddy just showed me his barstock milled engine, a 3M Mintor-110. They even machined the exhaust headers and tuned cans. Very pretty engine, but it hasn't been fired up yet. They also say it has a "lifetime warranty".