Several weeks ago, I sent an email to Weathertech asking the same question. They never replied, so I decided to take a look at the Infiniti mats. After examining all the custom cuts in the second row required to fit around the seat tracks, I decided it would be unlikely that anyone would offer the same level of fit.
The Infiniti mat set covers all three rows, the front mats have the JX35 logo and they seem to be of comparable quality to the Weathertech standard mats installed in our other cars. The Floorliner mats would probably do a better job in the front, but these are adequate for winters in our area.
Although my local dealer tried to charge $230 for the mat set, the online list price is $165, and you can also get 10% off and delivery for $14.95 from some dealers, such as Infiniti of West Chester, PA.