The DS821 servos I own have been great! I use them in five planes (40 & 60 size), and they suit my purposes very well. They are inexpensive, quick, powerful, accurate, and dependable.
All of the DS821 failures I have heard about were due to either using them in situations they were not designed for, or from the use of Loctite that broke down the plastic. I WILL NOT use them in planes larger than 120 size, or in glow helis larger than 30 size, because they weren't designed for that. For my large planes, I am using metal geared servos designed for that application.
I am switching over another four planes (90 & 60 size this time) to DS-821 servos this winter!
