When I first started shooting trad I used split finger release mainly because that's how everybody did it. I struggled with it for a long time and it always felt somewhat foriegn to me. I just never could get comfortable with it and I couldn't hit a barn door if I was standing inside the barn.
Then I really got serious about shooting and was determined to get good at it and I just happened to see someone shooting 3 under.......then it clicked. There is another way to do this!
I use my own modified style of 2 under because I feel like I get a cleaner release and it feels completely natural to me. My groups improved almost immediately and now I'm irritated if my groups swell to 6" at 20 yards, if that happens I'll be the guy in the backyard pounding the target with the porch light on well after dark.
I will never go back to split finger because this is what works for me. If I miss it's because I didn't judge the distance correctly or my form shifted, not because of where my fingers are on the string.
BTW- I have never had an arrow fall off the string using 2 under.