It's been a struggle but we have finally succeeded in getting our supply of Infineon based motor controllers modified appropriately to operate with a universal input voltage range. The 20 and 35A models have a 19V cutoff with regen up to 58V, and hence work fine from 24V to 48V packs. Meanwhile the 25 and 40A models with IRFB4110 mosfets work with 36V to 72V batteries, with a 26V cutoff and regen all the way to 88V. No more need to change resistors around to work with different pack voltages. Additional details explained on the controllers page which has recently been revamped.