This is one of my concerns with the Trijicon. I have a traditional scope (different brand) and it's too difficult to read the small numbers to be quick.
I have the post with the triangle and it's far too small for my liking.
If you're used to the Elcan C79-type optic, even that post at least takes up a large portion of the viewer so you can see it right away.
On the ACOG the tiny little post is this little thing in the middle, and in my opinion far too small.
You can barely even read the tiny font numbers for the drop compensator, either.
Happy with it overall, but I would have gone with the ring-based battle sight if I could choose.