I don't have a Burris to compare my new 3-18 to. Just received it this week. I looked pretty heavily through the glass today, both during some cloudy morning hours and also when it was mostly sunny. My current other optics are a couple Sig Tango 6 LPVOs, a Leupold VX-5, a S&B PMII 5-25, a Steiner P4Xi 4-16, an SWFA Ultralight, a Tract Toric, and a Delta Stryker 1-6. The T6Xi glass to my eyes is better than all but the Schmidt. And its not far off that, in fact I might say its equal, but would like to compare out on the range and side by side before I make that claim. The glass is just super clear, no yellow or blue tint to it like I often see on cheaper lenses.
I don't know if the T6Xi is German glass, but I expect it is. My other Steiner and the Schmidt to me are the best glass I own (although the P4Xi has some CA on bright sunny days), and both use german lenses. I had a Razor 1-10, and it didn't compare. The only other 3-18 I've ever owned was a Tango 6 Gen 2, and the new Steiner smokes it.
The eye relief is awesome, I love the green reticle (wish it was brighter), and the eye-box for a 6x erector is pretty forgiving. Now I want to try the 1-6 and the 2.5-15! Gonna have to wait though, as we lost most of a big tree during the recent wind storms, and cost to cover cutting down and removing would probably have funded both of those. Such is life.