"I know that on the newer trucks most of the electronics expect a certain amperage for them to work correctly. I have seen them where to low or to high of amperage will cause damage to electrical components"

Yeah, I thought about that too (which, amazingly, the GP techs didn't think about...they were fixated on the weight issue) and figured that would be the only reason the smaller batteries might be affecting the traction speed transistion. But now the pallet jack has a proper 600 AH Deka battery, fully charged, and that didn't help at all.

OTOH, what I thought about was the smaller battery bank affecting performance, whereas you mention actual "damage" I can sort of see that in a long term situation where the components are "stressed" for months but find actual damage hard to believe on something that acted the way it acted immediately, when the jack had one minute of use.