The JLD stuff is basically pre-PTR. That's just the receiver and a couple of other bits.It's been awhile since I researched it, but I remember that I give a bit of preference to the JLD stuff over the newer PTRs. Also, it's just MO, but I like that the JLD stuff is a little more rare...you know I like stuff that no one else has...
The OG JLD builds are considered top notch and you can identify them by the A-prefixed serial number. This build was done by Vector Arms, so it was still built from the same batch of parts, but has a B-prefixed serial. Obviously Vector Arms also has an interesting history and solid reputation too. The rifle has a lot of cool gun lore in it, but I don't think it's quantitatively better than a new PTR build, and that's comparing them side by side.