Recently got an MRX and love it.

My one and ONLY problem so far is the difficulty of popping in and removing the AA batteries. I have never owned a piece of electronics in my life for which this act has been so difficult. It really is a tight fit. At one point, I pushed on the battery so hard that the metal electrode dug into the corner of the battery and created an internal short (meanwhile, the battery was wedged in at the wrong angle and was heating up). I had to pry the battery out with needle nose pliers as the outer coat of the battery was starting to smolder!

(As background, I know how to properly pop in AA cells. I have a Ph.D. in engineering, am tech-savvy, and have been using consumer electronics for 40+ years. The problem is not with the user).