I went from a set of XS Big Dot sights to a normal front night sight and a dotless Novak RR. My group sizes went from ~3.5" to ~1" at 15 yards. I feel like I have lost zero speed.
IMO, they are a system which seems like they would be the best, but they are about the same. Accuracy is awful. My eyes never seemed to care if it was centered in the V and the bias of the V on bottom always made me shoot low.
To add to this, I would avoid TRO's also. They are too big for their mounting foot size...read can be moved by a moderate impact.