Rich,
 
Go to the technical articles under the members tab and you will find a couple good articles.  I am in the middle of installing ev 200 below deck right now on my MK 2 also.  The ev100 is the wheel drive unit?  That is what was on SlipAway when I purchased her 3 yrs ago.  What little it worked before control unit gave up I was not pleased with performance?  That is why I replaced with the below deck ev200.  For what it is worth?    

Mike Willis

Another data point - Fin keel, eliptical rudder, std. rig, does great with the wheel pilot.

Adding a rudder position sensor made it perfect. Without it, the computer needs to guess - and they don't guess well.

According to Raymarine, the EV-100 / 200 are the same as far as navagation logic goes - the 200 has larger curcuitry to handle the increased power draw for a larger drive and the associated on/off solenoid/clutch circuit.

Originally had the 'rate gyro thing' in the storage area right in front of the galley sink - not so good when you put a shop vac and other magnetic junk in there. Moved it to the lower part of the 4-drawer cabinet just opposite of the head entry. Perfect, but do pay close attention the contents placed nearby.