Nick
Unfortunately the MM pick-up and the pre-amp work together. If you change the pre-amp to anything other than the MM then you'll lose the coil switching.
It is possible to replicate the coil switching using a multi-pole switch but you'll get a volume change between settings and you need to rewire the pickup slightly. i.e. separate the coils and add an extra wire. I went through several combinations (East, OBP3, Duncan, Bartolini) and settled with an Alnico Nordstrand MM5.3 pick-up and a stock MM pre-amp. It works for me.