I have the spitfire and the Burris ar1x. I prefer the Burris for 3 gun, simply due to the long-range capability but other than that they are pretty similar in my eyes. I put the vortex on my steel challenge 15/22 and that is a dream come true. Both optics are bright and hold zero well. I guess to be simple the only real difference I noticed was the Burris takes a AA battery which is great, and the reticle is a lot friendlier for distance targets on the Burris. Ran like a champ this last Saturday at our monthly match, Pat Kelley had graciously lent a Co2 powered pop-up target to the match, set up at 250 yards, and it wasn't obscured by the center dot.
Hope that helps.