I have always shot three since switching to traditional some twenty odd years ago. I never really had a problem tuning, but as stated above, my nock had to be a little higher. When I bought my first longbow a few years ago, I was trying to shoot that the same way, and it wasn't working for me. It was loud and I couldn't get consistent arrow flight. I started shooting it split and it was night and day different, the bow was a lot quieter and my arrow flight was way better. As McDave said above everyone is different and what works for one may not work for another. I still shoot three under on my recurves, but shoot split with my longbows, It take a few practice shots to get dialed in because of the difference in my finger placement on the string.
Jason