Anecdotal evidence, I know, but still--nothing but (reliability) grief with MD-3; gave up on them altogether entirely after missing shot after shot. I work my drives relatively hard, pretending the digi revolution never happened--MD-2 is worth its weight in gold... Hey, just think you're holding a gold bar, it might work!
PS. Have you tried lithium AAs in the MD-2? Noticeably lighter and faster.
Did the gears in your MD-3 break?
I LOVE lithium batteries. I started using them for their lighter weight, but they also seem less likely to leak.