spickering

I'm coming up on 6 months since I bought mine (from Woosh). It definitely feels a step up from the TSDZ2 in both power and build quality. I think the only niggle I've got with it at the moment are the assist levels - it almost feels like when they downrated the motor they didn't change the the power targets. Level 1 assist is a nice low/mid boost, 2 is a lot of power, 3 and 4 feel almost indistinguishable from 2. It works fine for getting around but I do miss having finer adjustments. Does anyone know if the number of assist levels are set by the motor or the display? I'm currently using the included VLCD5 - would a different display allow for more assist levels? Or alternatively, is there firmware available that adjusts the power levels?