Just wondering how much taller it is because with the Larue riser on my EOTech, I can hardly see the fsb at all.  Wondering if I should sell the riser or install a F marked FSB.

with the Eotech on the Larue, you get a lower 1/3 co-witness, if you dont like it that low, and want an absolute co-witness remove the riser

1. The F marked FSB isn't any taller except for the flat section at the base of the front sight post so that the post can go a little taller without wobbling around.  If the irons are zeroed then the front post is going to be the exact same height as it is now, there'll just be a little less of it visible above the FSB.

2.  Swapping the FSB is not a trivial task, your best option for doing so it to replace the entire barrel with one that has the FSB you want already installed.