I've cast with quite a few MP HP moulds and have found them to be the easiest "production" design to use, by far. The most I ever had to to maintenance-wise to the guide pins is lightly polish a burr that I created when my pliers slipped trying to install one of those "Jesus" clips. I never needed to lube the pins in any manner, either. The advise to keep them about 1/4-1/2 turn loose in the spuds is good, but keep an eye on it because they tend to work their way out.
My biggest challenge with the big, brass, 4C MP HP moulds is to be able to run the smaller calibers fast enough to keep the pins hot enough to make clean cavities and not have that little bubble in the bottom.