I've owned several over and unders in my life, and some Brownings.
My worst fear with any over and under is getting one like my friend bough new a few years ago. When patterned at 40 yards there was 18 inches difference between the POI of the top and bottom barrel when holding to the same POA from a bench rest. This was the worst I had ever heard of. This was a high priced, famous name brand gun. After several months of going back and forth with the manufacturer, he finally got them to take the gun and refund his money.
Another bad one, I personally patterned for another person. There was 12 inches difference in that one. Most of the others I have patterned were acceptable if you were willing to accept as much as 4 inches of difference.
Not trying to discourage you, but just letting you know that when you buy a new over and under of any brand you take a chance of getting a gun like I described - even with expensive guns. I saw test results once on an $8,000 dollar O&U that was almost as bad as the first gun I mentioned.
I already have all of the O&Us that I will ever want, but if I did decided to buy another one, it would be a used gun that I could pattern before I bought it.
If you decide to buy that gun I would ask the question ahead of time about how close the two barrels are guaranteed to shoot at 40 yards. If you get a solid guarantee on a number of inches that you would accept, then I would buy it without hesitation. Otherwise I wouldn't buy it.
Good luck.