DMPS is often reported to be much nicer than DMSA. However some people, including me, have done fine with DMSA + generous amounts of other antioxidants.
Some can only do a round with DMSA monthly or even less due to candida flares or other immune system issues. A friend is one.
A Cutler would say you are not taking enough C and E while on round. My head felt much clearer when taking more than skimpy amounts of E.