I would avoid paint-on primers with minis. The only time I use paint-on is for spot repairs prior to painting and on scenery...sometimes, usually if something is too porous or under cut and I cant get spray-on to cover.

Paint on primers then to be thick and have settling/leveling properties that make them undesirable for fine detail as they ten to fill crevasses. It will probably look ok after it dries (and typically shrinks), but you will have lost some depth to your detail.