That is a rather common thing with cvd's you can easely prevent that, creating a little notch on the pin that goes thru the cvd (in the middle, were the setscrew touches the pin) and you can screw in an extra screw. i use two types of screws to keep it in one piece. a cup type (due to the deforming of the material it keeps itself in one possition (among with some threadlock/loctite) and one with a flat head, on the other side. it works like a charm. With the notch in the pin they won't come out with one screw though..
Those rd-logics are very good too.. (great value/price) i read negative things about them on other forums, but Mike is very enthusiastic about them. (he uses his trucks allmost 24/7 :p)
And yes, that is the notch i am talking about.. Don't make it too big, because your pin can snap.
I know people who use their MIP's with great succes as well.