Between milk of magnesia (magnesium hydroxide) & mag citrate, is one less likely than the other to cause cramping? does one pull fluid into the bowels slower maybe?

They are similar.: Both milk of magnesia (magnesium hydroxide) and magnesium citrate are osmotic laxatives, drawing water into the bowels and stimulating bowel motility. Used in similar doses, they should act about the same, although certainly one may be better then the other in a particular patient. You have to learn what works best for you. It is advisable not to use laxatives on a regular basis. Good luck