I have the same issue going on as David. I use a Bateman cordovan tab, split finger, with a spacer. I do have equal callusing on index and middle fingers. So, more finger curl on the string may help with this? I do like less curl (but just enough to keep the string there) because the middle finger goes right into the corner of my mouth better. So far, the joint discomfort there is slight, but I wouldn’t want it to start getting worse as time goes on.
