Most of the problems with Magnum carbs seems to come from the O-ring on the needle valve.
If it's new it shouldn't pop up as problem for a while at least. I've had good luck with Magnum engines. I have a 52 4 stroke that is going into a Fokker D-7. One of our club members flys an OS 52 4s as well as a Mag 52 4s. He claims there is nothing to choose between them. I used a .46 in an LT40 and it was very reliable. I'm also considering the .52 for another airplane. Go for it.