I cant speak on long term durability, but aesthetically the GM Jams blow the authentic 2009's out of the water.
09 Jams were pure trash :x :x
Joints literally look worse than fakes :x
That's not fair though. 09 Jams were some of the worst retros we've ever seen. Also, something you're not addressing...even though you did mention longterm durability uncertainty is:
The shape of GM Jams are terrible. Puffy collars alone make the shoe look ridiculous. Also, they phylon is usually rounded off in the back and the 23's look stretched and funny.
Also, you have NO idea as to how bad the internal construction might be. Possible flat airbag, funky stitching, etc. While they look better at first glance, I'd still rather have the original knowing I'm getting all the components in the correct fashion, and not some slapped together model that looks better but really isn't.