I fly 1000 mile cross-countries several times a year. At first did it all in my C by hand. Arrived at my destination too tired. Then like you I gathered the parts and installed an Accutrak II first in our C. It was a fantastic magenta line follower. But, after I finished my IR and started asking for diversions around buildups I started to covet the Accuflite. Installed that my nav problems were all solved. Life was so good, except for altitude hold.
Next I pieced together the parts for the Brittain AH system, and with the help of some resident knowledge here, got it working. Ended up with a full two-axis autopilot, all done by tubing and rubber bands!
Now I fly a J with a "modern" autopilot- the 1980's vintage Bendix-King KFC-150. Honestly, the Brittain wing leveler does a better job than the BK at keeping the wings level in turbulence because it is more responsive and smoother. The dynamics of the Brittain wing leveler are just unbeatable it seems. The altitude hold on the BK system is very aggressive at maintaining altitude within 20 ft. The Brittain altitude hold had more like a +/- 60 ft variance, and provided a much smoother ride. In mountain wave turbulence I just have to turn the BK altitude hold off or it will make my passengers (or me) puke. The Brittain altitude hold, while responsive, seems a better match for the flight dynamics of a small airplane.
The Accutrak II would sometimes wander a bit. Seemed random, but more likely to happen after several hours of a long trip. The Accuflite of course depends on the rate of gyro precession on your DG- that would make long distance flights without the Accutrak a little zig-zaggy.
If you can find all the parts, I'd recommend putting in both. You can use the Accuflite to help in maneuvering (e.g. holds) too if you need to look at an approach plate or weather data on your iPad while shooting an approach. It's all great for workload reduction.