Thanks guys for the replies.
TDW, I was looking at Coursemaster as the current hydraulic steering in my boat is Hydrive and Coursemaster are the distributors of Hydrive units. As the hydraulic unit has been working almost 30 years without any major issues it sounds like their products are pretty good.
I was also a bit concerned about compatibility of the Coursemaster controller with the Benmar / Hydrive hydraulic unit. However I have now worked out that it is fairly common to use a different brand controller with the drive unit. Coursemaster's website specifically mentions that their units are compatible with Benmar drive units (as well as Raymarine, Simrad, Comnav, TMQ, etc). However it is not with the CM85i but rather the CM800AC-HD, CM850AC-HD or CM650AC. As these look like beefy commercial products it's probably not a issue (except probably more $).
The other thing that attracted me to Coursemaster was when I read David Adam's book "Chasing Liquid Mountains" when he won class 2 of the BOC around the world race in 1995. His main autopilots were Coursemaster 600's. In the race the Coursemaster's worked fine. The only problem he had was that the autopilot was "without fear" and he had to handsteer for 48 hours in a 50-60kt storm in the Southern Ocean to stop the boat from capsizing . Apparently this storm had 12-18m (40-60ft) waves and his 50ft yacht was surfing down the waves like a big longboard.
Overall it sounds like Coursemaster are good reliable products. TDW, like you said they are not very well known outside of Oz.
Valiente, thanks for the suggestion however neither ComNav or W-H Autopilots appear to be available locally. My local chanderly stocks Coursemaster, Raymarine and Navman products.