Big Dots for me!
I'm middle aged with bifocals. I have a few guns with tritium sights but they are all traditional 3 dot configuration.
With all 3 tritium vials of the same color, I was having problem ensuring that my front sight wasn't actually outside of the rear sights during low light training.
So, when I purchased my XD9sc last year, I ordered the Big Dot tritium sights and had them installed at Springfield's custom shop before they shipped the gun.
Sight acquisition had a marked improved from my very first range session. Since then I've gotten better and better and love them all the more.
I will add XS Big Dots to more of my guns as the tritium of the old sights fade out some more.
I've had my G-23 about 11 years now and Trijicon's are definitely not as bright as they first were.