I did an awful lot of research on both companies before buying my PP50. If you look back on WW, there is a long history between Longevity and Everlast. From reading these old WW posts, it seems that Oleg, from Everlast, and Simon, from Longevity, are brothers-in-law.

That being said, in the research I did, Everlast products seemed to have better reliability and Oleg seems to stand behind his products much better than Simon. My 2 cents...