I owned the deathadder for about 3 or 4 years, and both of the ones I owned developed the double click issue (I had to replace both with my own money as the warranty was up). I recently purchased the RGB M65, and I have to say I like it better than the deathadder so far.
It is a bit heavier (thanks to the internal weights, that can be removed), and wider than the deathadder. It seems to fit my larger hands relatively more comfortable, and the extra 3 buttons in comparison are nice as well. The mouse 4 and 5 buttons are further out of the way as well. Mouse wheel is more "clickly" better to use in my opinion.