Even Mainesail is still using the wheel pilot last I knew. He bought it for the brains with the intention of using it as part of a below deck unit when it died but it hasn't yet.
Jesse I have had a linear-drive for a number of years now after the wheel drive failed. I carried a spare so was able to swap it out while sailing. A few rags in the scuppers and it can be done. Only had to heave-to for about ten minutes total to get it swapped out..
The big difference here is duty cycle. We do 1000-1200nm per year mostly coastal. The CS-36 tracks like it is on rails and balances very easy compared to our old 310 which was pretty
squirmy, comparatively speaking, downwind. While the CS is grossly over the wheel drives weight capability limits the work load applied to it on the CS was likely less, especially down wind or with a following sea. We also had a rudder reference and the wheel unit was inspected and fixed, if needed, every winter. It drove our 20,000+ pound CS for many years and I was surprised it did/could.
The key is that when I installed the wheel pilot I did not buy the
wheel pilot kit, I rarely if ever do
.. I installed the below deck brains for the linear-drive and then used it with the wheel-drive. This meant the course computer already had the clutch drive circuit, which you don't get in a wheel drive kit (Raymarine is smart about this). It also meant that when, not if, I upgraded to a linear-drive I would not need to replace a perfectly good course computer. This is how I suggest installing any wheel pilot for an owner who is even teetering on the edge of below deck or above deck. It costs a tad more up-front but saves money in the end.
The performance differences of the new EVO's is pretty dramatic but not dramatic enough to fix your issues, for your duty cycle, while keeping the wheel drive. Your duty cycle really requires a below deck drive or to carry a spare wheel drive at a bare minimum. The EVO's still need a rudder reference sensor, don't be fooled by this... If your 4000 does not have a rudder reference START THERE.....
A below deck unit is a big job to install, especially in the water. I had one rudder shaft that took two days to drill through, cramped and upside down. A few shavings at a time so as not to work harden the shaft. The owner refused to do a short haul, to drop the rudder, and in the end it would have actually cost less. The tiller arm can take a month or more to get too. You do not want to connect the RAM to the radial drive. I have seen the results of this three times and it's not pretty. I prefer the bronze Edson tiller arms and they can send you the work-sheet...