On my Wellcraft 290 Coastal w/twin 225's I installed a Raymarine S1G course computer with the ST6001 control head. My only issue came from the rudder reference unit. I had the linear "outboard" unit and the rotating cylinder SeaStar ram at the engines tore the linear unit up internally. Once I went to a potted rotary rudder reference unit, it operated flawlessly.
On my current boat I have the SPX30 with the ST70 control head, and LOVE IT! There is NOTHING about this setup I don't like.
I'd heartily recommend a Raymarine AP system.
Joe