I run both brands, (DA & 3W0 and if the instructions are followed for starting and break-in you will have a fine model airplane engine. It's been my experience that "finiky engines" are usually the result of mis-steps in the breakin or setup proceedure. Of course there some actual experts, much more knowledgable than myself, on here that would have more in-depth and substantial comments on this. Further, based upon my experience with both companies, I'd arrange to send the engine in question back and they'd be happy to troubleshoot/correct any problems with it.