New Combi Boiler and Existing Shower Problem

[dozer]

I'm about to replace my old system boiler with a new combi Vaillant EcoTec Plus 837. I'm wondering if anyone can recommend what I should do with our shower. It's an Aqualisa Quartz A2 that works by mixing the hot water from the cylinder with cold from the mains, and has a pump to increase the flow; the on off switch/temp controller is electronic. I think I have three options: 1) Try using it and see what happens and risk knackering the whole thing (could be very expensive); 2) As recommended by Aqualisa, replace the control unit (which contains the pump) with an "operator" and fit a new on-off switch (horrendously expensive), 3) Try disconnecting the wires to the pump within the control unit and hope that the electronic mixer controls still work.

Has anyone else tried this or can anyone give some advice?