We're spec'ing a Simrad based AP for our V42 as well.
Simrad AC42 Computer (N2K)
Simrad AP28 / AP24 Control Heads (N2K)
Simrad HLD2000 Mk2L
Simrad RF25 RFU (this one is N2K)
Airmar H2183 Heading sensor (see YouTube here
The Simrad / Robertson drive unit seems to have a very good reputation, even identified by Evans and Beth on their list of top rated equipment you can find here
We did not consider Raymarine at the time, so can't help you there. If you already have most of the Simrad equipment, why not complete the rest?