Regarding the Dawson sights...I have a Gen 3 Glock 34 with a Dawson fixed rear (.115 notch) and a Dawson fiber optic front. Dawson recommends a .205 tall front sight for this set up, so that it what I initially ordered. Once installed, the .205 tall front shot about 5" high at 25 yards. I used the calculations on Dawson's web page for front sights and ordered a .245 tall replacement. The gun is now spot on for point of aim at 25 yards.
I recently switched to the Dawson sights after a year of shooting with the Warren/Sevigny narrow notch (.130) rear from CPWSA and the matching .245 tall fiber optic front. The sights were great for target acquisition, but I simply could not shoot longer shots as accurately as I wanted to. The switch to the Dawson sights, especially with the design of the Dawson fiber optic front, has given me a much crisper sight picture and much improved accuracy at longer distances.
As an aside, the 34 is my primary SSP gun for IDPA. Last week I surpassed the 10K round mark, and the gun has functioned flawlessly since I bought it new last year.
Rick