1.) The saddle springs rest against the strings when the strings are at full tension. The springs move slightly during play and throw the guitar out of tune. Nightmare.
2.) The saddles, because of their design, actually tilt to one side when one bends the string while playing lead. The saddle actually tilts up onto one of the adjustment screws, leaving the other screw actually off the deck, which in turn allows the screw on that side to loosen and throw the action/intonation out of whack.
Overall, this is a very poor design. I would not recommend this saddle to anyone because you will probably end up having to send it back and purchase a different one anyway, which is a total waste of valuable time.