One can add a potentiometer into a solid state VR without too much trouble if adjustability is wanted, though I like the old stuff sometimes. I'm not sure if I would want to use a thermo-mech VR if I ran anything OVER 60 amps though, and I'm looking into getting something in the 95-100 amp range now, given how summer heat directly attacks the charging system, PLUS using electric cooling accessories to compensate....