The 5x15 on top of a MarkX in 223 is one of my favorites. The sun shade is very effective when shooting to the west late of an evening. And yes the Rain Guard does work!
Larry, the Firefly reticle is for lack of a better explanation, a distraction. It serves no purpose for me. This is one of those things you may have to look at for yourself to understand and you may like the result, but I don't know anyone who has tried one that liked it.