I've been in the tactical shooting arena for more than 15 years and have used Leupold MK 4's, IOR's and now own a US Optics on my tactical rifle.
Leupolds MK 4 glass I would rate as just OK or average. IOR's glass is incredible and well US Optics glass is the best I've seen or used.
A couple years back I built a gun for moose hunting in Alaska. .300 WSM LH Win model 70 Featherweight. I didn't want a heavy scope so I went with the Burris 4.5-14X32mm Short Mag compact scope. In the Burris brochure the Short mag compact's glass is listed in the good category and not there best.
I love the Burris short mag scope and the glass is really fantastic. Now it's not as good as the IOR or US Optics glass, but it's a lot better than my Leupold MK 4 glass and it's only Burris's good glass. Their tactical scopes come with their best glass, which I'm guessing would be outstanding glass and it's a lot cheaper than some of the other big name high priced scopes out there.
I've never had a warranty issue so I can't talk about their customer service, but did talk with them about changing the duplex reticle to the ballistic plex. The tech said send it in with $50.00 bucks and it's get taken care in a day or two from receiving it.
I like the Burris short mag so well I put one on my son's Model 70 featherweight .243. Good chance my next guns will wear a Burris