Dunlops have a misearable history of performance on Q45 starting when they were an OEM alternative in 1994. There is a TSB from back then on them.
I read
http://www.tirerack.com/tires/...1=yes and the chart
http://www.tirerack.com/tires/...c.jsp to conclude the Avids were not up to snuff, except for Park Avenues.
The only Yokohama I would get is the AVS db S2.
Hate to say it, but it sounds like your guy has limited stock. Surely he can order in a set in a few days?
If you are in Jersey, and not doing high speed summer runs, I would look at the XGTH. Quite frankly, based on the tire rack query in 255/50-16, they are the only tire I would consider. In 245/50-16 you have a few more choices. My advice is don't skimp on construction and quality. The only remedy is replacement sooner than expected of the bad choice.