For my 'ol eyes I tried Dawson FO, TFX Pro, XS Big Dots, SIG X-Ray3 etc and although better than factory sights, none of them really allowed me to see both the sights and target simultaneously at distances much past 10 yards. Sucks getting old.
Finally solved the issue by having CZC mill my SP-01 TAC for a DPPro Red Dot. Bingo!!
After a short learning curve I'm able to just focus on the target and place the dot. Fast and Accurate again out to 20+ yards.
Just Say'in...There's more than one way to skin a cat!