Couple of things. I am not the one to talk to about hydraulics's mentioned elsewhere in this forum (and with a vessel of my size and weight), I've been there - done that and the reason I now have a simple non-hydraulic system.
I suspect this is your first challenge that you are going to have to address rather sooner than later and stick to your decision. Regarding our ocean passaging, in our case, this was discounted during the 'buying the plans' stage and to date we are very happy with that decision.It got me thinking about redundancy and having back ups if we ever get as far as long ocean passaging.
We have been very pleased with our system and the redundancy is twofold. If the electronic guts fail, you still have manual engagement of the Raymarine wheel pilot itself, engage the clutch and it will hold the wheel on a fixed course (with no electronic tracking and wind function corrections) - heading if you like (not strictly correct for the purists). So you still have basic course holding while you do other things. The only way this can malfunction is if you physically break the clutch or something else untoward happened in the wheel pilot section.
If the first two options failed, our last resort is to hand steer.