There are few guys that had success, and a few guys with galled push rods and broken adjusters.
Hard to say if the bad adjusters were due to incorrect push rod length keeping them from getting oiled properly or manufacturing problems
My machinist used a few on some mild FEs he did for a local customer and says they are junk, but when I asked him why, he seemed more pissed off about setting them up than quality.
For me, I am not sure I'd buy them at all, but if you do, don't buy them direct. They are available for over 100 dollars cheaper all over the web.