dk_erickson, thanks for the kind words, I'm very happy with the setup.
The front sight post and ARMS #40 do co-witness in the center of the EOTech field of view, but it doesn't interfere with the use of the EOTech reticle.
I might suggest zeroing the BUIS *with* the EOTech mounted, as there have been reports that the refraction from the optical sights (EOTech, Aimpoint, etc.) can change the BUIS point of impact, when compared to looking through the BUIS without the optics in between.
If I need the BUIS because the batteries or reticle are dead or the lens is broken, I won't have time to remove the optical sight, I'll just flip up the ARMS and look through the optical sight (hopefully it won't be so smashed I can't see anything through it).
You might consder the Santose improved battlesight zero (IBZ) for the irons (look at the bottom of the page):
[url]http://groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw[/url]