I shot split finger most of my life. There were various times when I was younger that I would try 3 under but, quickly abandon it in just a few shots because I didn't hit what I was looking at. Last year I finally made the switch to 3 under and gave myself more than a few shots to make the correction. Within 50 arrows my brain had made the correction and in a short amount of time I was shooting better than I had ever shot. The difference in my shooting the last two years is noticeable enough that my dad has also switched to 3 under after shooting split finger his entire life.
Both of us struggled a little with face scrapes and hitting our noses when we made the switch. I just had to consciously pay attention to my head position for a while but, it's now part of my form and I don't have that issue anymore.
I have helped several people get started with Trad the last two years and I recommended to all of them to shoot 3 under, the arrow being closer to your eye really helps.
Edit: The only 'pro' I know of to split finger is if you are shooting longer shots, it makes your point on farther away. This is why a lot of long range target shooters shoot split finger. At the distances I shoot in hunting situations that's actually a con.