I posted early on this thread but want to add some stuff.
I have been shooting 3 under since the late 60's. Changed from split when a really good target archer told me to try it. This discussion has been going on for a long time. Seems we will always have the question.
I am truely more comfortable with three under because I have more confidence in it. I can also say that over the last bit of time, even as old as I am, I have finally refined my anchor to one spot. However, I have experimented with string walking a bit. It works like a charm at closer the POI distances. Since we are bowhunter who take good shots it makes sence to me. Think turkey out of a blind situation at 15 yds or so.
Your bow does not have to be tillered for 3 under. In fact, of all my bows, only the one that is currently on order is/will be tillered that way.
I think the allignment under your eye makes the difference. Now, that having been said, I know some tough three under shooters that do not anchor under their eye. The still shoot lights out.
Guys, its like choosing to shoot trad... Its a personal thing. What ever floats yer boat. However, take a look at the really good recurve and I think Long Bow NFAA shooters......