I waited all summer for the X-5, Raymarine kept delaying the release so I gave up and got the S1. I've never used an autopilot before, but the S1 seems pretty solid to me. It really increases the enjoyment I get out of sailing especially since I'm solo a lot of the time ... got it linked to my GPS which is really nice. Seems plenty powerful for my 30ft boat. Issues I've had so far -- a couple times the autopilot has suddenly stopped tracking a course without warning, and the autopilot's compass doesn't match my boat's compass despite calibration (could be a mounting location problem).
Installing the rudder sensor didn't bother me that much, from what I understand having a rudder sensor is a good thing ... should increase the accuracy of the autopilot (it's still available for the X-5 as an upgrade, and IIRC the better Raymarine autopilots will still include the rudder sensor). The toughest part for me was removing the wheel, it was really stuck on, had to buy a gear puller. Here is my mount for the rudder position sensor, just took a little bit of planning (Halekai AKA Maine Sail's posts helped me out for inspiration):
1980 S2 9.2A (30') in Anacortes, WA
Aux power 13hp Volvo MD7A