I finally decided to try a piston build.  After a lot of thought and going back and forth I finally decided on a Superlative Arms piston kit around a Lanco Tactical receiver set.  I also decided on a RA/Fortis Switch rail for ease of piston cleaning.  Barrel is a Voodoo 14.5" middy with pinned manimal flash hider.  The piston block barely fit under the rail...but it fit.

Up to this point it has only been test fired at the wide open position.  Looking forward to a range trip.

One question...would you even bother putting BUS on a rifle with a switch rail...seems your return to zero would be garbage.

Here is the kit I used.
http://suparms.com/collections/retrofit-piston-kits/products/750-adjustable-piston-system-mid-length-clamp-on-melonited-low-pro-ar15

Looks good. I just took my suparms kit out this last weekend and it worked great! If you have any questions about tuning in the gas block before you get to the range let me know.

How you liking the mepro?  I have one and on the brighter settings there appear to be almost a horizon and a halo around the main dot.

I love mine.  I think it is on par with my Aimpoint PRO.  I agree that the higher settings are too bright unless in direct sunlight.  I would rather of had one more low setting.  All in all, though, it is a minor gripe.  It just works.

My range report is going to have to wait.  I went back and started messing with it because I did not have the gas bock aligned how I wanted it.  When I torqued the screw on the clamp I broke one of them.  

The good news is that Tony at Superlative arms is going to remove the screw and put a new on in for me if I ship the block back to ensure I don't damage the gas block.  I called him to see if I could get a new screw and he offered to fix the issue for me at no cost.  Customer service at Superlative Arms is definitely above and beyond.