Exactly. It's heavily base don McQuarrie's original concept art. Look at Rebels (the series), it uses a LOT of MQ's concept art, from R2 and Chewbacca to Jabba and IG-88. Even the Ghost (the ship) is based on an old unused design (albeit not one by MQ). Also, fun fact: in MQ's concept art, lightsabers produced thicker blades than what was eventually used for the rotoscoping in the OT, and Rebels used thinner blades.
But back to the topic of the X-Wings: as a kid I always wanted one of those LEGO X-Wings (I had/have several of the original LEGO SW sets from 1999-2001, but none of the orginal Rebel or Empfire fighters except the very first A-Wing), and as an adult I finally got around to purchase one of the newer X-Wing sets. And then Disney went straight ahead and created the new T-70's (the OT ones are T-65b's) and I was all like DANGIT. I actually like the new X-Wings. They really took the design and made it even sleeker and more aerodynamical. I'm kinda "eh" about Poe's odd orange/black one, but I like the "default" white and blue ones. i never really truly enjoyed the way the red stripes/decals were drawn on the OT X-Wings. I like how the newer ones eliminate the "beak" on the nose and instead of having four barrels for engines, it looks round and smooth, creating the illusion of two engines splitting into four.