I would strongly recommend the Trijicon HDs. I had XS Big Dot sights on a Glock 26 and I hated them. They shoot consistently high, and yes I am using the correct sight picture. You can get fast hits *roughly* on target with them. I will certainly give them credit for being fast, getting that golf ball up and covering the target fast is very easy. But the point of impact is anywhere in a 5 inch or so circle for me.
I've found with traditional three-dot sights, once I get used to the gun and how it points, I can quickly bring the gun up the same way and get the same results, the sights are perfectly lined up right where I want them.
The Heinies are the same concept as the X/S, except I believe they are a little smaller, allowing a little more precision. You also get a better rear sight to line up with the front. I would prefer them to the X/S sights for this reason. However, I'd probably have the same complaints. I will take accuracy over speed, because I believe the speed comes anyway with familiarity, and I believe traditional three-dot sights are more accurate.
Just my opinion though. There are a lot of smart people who really like the "dot the i" style sights.