Mark, I have received mixed opinions on if the Raymarine X5 will work but I am going give it a try as I also don't want to spend $6k for a hydraulic or electric linear drive unit.
Last year, I purchased all new Simrad instruments and a NSS7 chartplotter but I have recently changed out and replaced with Raymarine ST60 + and C90W chart plotter, and installing a sea talk network. This will be a plug-play for the X5. Selling most of the my newly Simrad and replacing with Raymarine cost more but not nearly as much if I want with any of the Simrad autopilots.
I figure that I will use it mostly when I am motoring for long distances, specially leaving in the morning or at night where there is not much wind, and when sailing in a light breeze. I would assume our S2's are near 17,000 lbs near full laden displacement and the X5 (rated for 16,500 lbs) would have a hard time keeping course when there is a strong current and breeze. Which I am okay with, if the wind picks up, I would rather be at the helm, controlling the trim and weatherhelm.