There definitely a difference in stiched edge quality from manufacturer to manufacturer (can only reference by vendor and who they choose). The deskmats I own from Novelkeys are flawless on the edges whereas other vendors have been spotty. The sushi deskmat from Kono that I received recently is a travesty – there are gaps in the stiching everywhere, rough spots on portions of the fabric surface, and the colors couldn’t be further off from the renders (possibly proto photos). I have definitely observed a direct correlation between quality and the mat thickness that the vendor chose.
The 3mm mats tend to not only be a less expensive option, but a lower quality all said and done. I recently purchased the Linus Tech Tips mat and have been really pleased by the texture and quality (I know they put a lot of research and money into it).