I've had 3 years of IPSC, (about 8 matches/yr), and some IDPA, and shoot well with irons. Just put a dot on my Shadow and don't have much through it and no matches. In playing around, I'm finding my slow fire precision is insane with the dot, but fast target transitions are slower because I'm getting so much information from the dot moving around, and that delays my shooting. My brain doesn't register that precision with irons, so I'll lob off shots that are "good enough", and they usually are.
Does that description make sense? Was your experience similar?
I get what you are saying and my experience was somewhat similar. Not sure about your eye issues but you are losing a huge advantage of the dot by not shooting with both eyes open and this likely leads to you spending too much time focusing on the dot. That is the big reason for practicing with the dot taped across the back, I actually shot a few matches that way early on as well and dry fire that way during the odd time I dry fire.
Basically once you start to get the hang of the dot you will never let it settle you are basically shooting a moving red streak for lack of a better description. If you saw a perfect dot you spent way too much time aiming unless it was a seriously tough shot, not unlike deciding what was an acceptable sight picture with irons.


















































