Having had three PTR rifles, two with the infamous "AW" serial numbers and now, one new G.I. with the GI serial number. I have to say go for the G.I. Model. You have the advantage of KNOWING the history on the gun as well as a good warranty. I was LUCKY in that both my "AW" guns were below the approximate AW1600 serial where the barrels STOPPED shooting anything but American Eagle or other new, commercially made ammo. These two shot anything I ever tried in them without a hiccup, while a good friend's gun numbered around AW37XX would CHOKE ON ANYTHING not new and in .308 caliber. Every JLD made gun I have seen or tried has been just like a HK in shooting ANYTHING fed to them. I agree completely with tcr39 about the JLD guns, but think that PTR has FINALLY gotten things right with the new G.I.Model. Knowing they had ammo compatibility troubles and NOT allowing these troubles to be "officially" recognized for what they were, then doing NOTHING to help owners cure them is inexcusable. The G.I. model corrects all the flaws in their guns but does nothing to help the thousands stuck with an "AW" gun that won't shoot surplus ammo. There is a post on this site recently (sometime in the last couple months)stating that all the NEW PTR built guns have the new model barrel and WILL reliably fire ANY ammo used. This is according to PTR Company spokespeople at the recent SHOT SHOW.
I recently sold the PTR karbine I had and got a new G.I. to replace it. This gun has (I was VERY surprised by this!!), a Rhinemetal bolt carrier with a PTR (US made) bolt head. Also most (if not ALL) of the trigger pack parts are US made and the stock sets appear to be surplus (undoubtedly POF). This allows you to change to ANY stock set you want and still stay within the 922r rules. THOSE WOOD STOCK/HAND-GUARD SETS AT RTG or CTD SURE LOOK GOOD ON THE G.I. GUNS!!!
Having had three actual HK's (2 HK91's and a HK93) back in the Golden Eighties, I find the quality and finish on ALL the PTR's, JLD made or PTR91 made is fairly close to, or even equal to those HK pieces I once owned. The PTR-F, Standard Rifle, serial AW12XX I still have (along with the G.I.) is slightly more accurate than the two original HK91's I once had, but not by much. It also doesn't have the same "balance" of the original 91's since it's barrel is a "heavy barrel" contour. To me, these are slightly front heavy (NOT A REAL PROBLEM), but the accuracy level makes up for this.
My G.I. has the original HK G3/91 barrel contour and feels (to ME) more balanced, exactly like the old HK 91's did. It shoots (GROUPS) more closely in size, to the heavy barreled PTR rifle than my old HK's did back in the day. ANY of these guns, JLD made or PTR made will serve you VERY WELL!
If you can find a GOOD condition JLD gun and that's what you want, GO FOR IT!! The major advantage of a NEW gun is a warranty, IMO. If in the PTR range you can get a gun with a serial BELOW AW1500-1600??, it also SHOULD shoot anything you want. I can attest to the fact that the new G.I.'s WILL SHOOT ANYTHING!! (as will MANY online reviews!)
I don't think you could go wrong with a new PTR (I got all of mine from CDNN) but if you want to be able to shoot ANY ammo you have/find (Military Surplus), by all means get a G.I. model.
Both of my guns shoot DAG German "Battle Pack" ammo I got from CTD really well, and very accurately, as well as also liking Radway Green British surplus. I have yet to experience a single feed/fire/extract problem with any of my PTR products (LOTS of rounds downrange).
You will undoubtedly have to browse the used gun market for a JLD model but, but they are GREAT guns. I just happen to love the guns I have owned by PTR. I looked at 2 used JLD guns before buying the G.I. and they were priced higher than the new PTR's, GI or Standard Models. Just be AWARE that the "AW" guns will PROBABLY not shoot surplus well (except Lake City surplus) and PTR says it's due to the AMMO!
I'm a former licensed gunsmith (retired due to health reasons) and did a nice trigger job on my two AW guns, but (lets hear some other opinions/feedback on this) the G.I. with it's US built trigger group actually feels almost their equal in smoothness and pull weight.
Sorry for being prejudiced but I don't think, dollar for dollar, you can do better than a NEW G.I. model at present. With HK parts being priced where they are now, and STILL LEGAL (almost everywhere), these are some sweet shooting and economical guns.
GOOD LUCK AND LET US KNOW WHAT YOU DO!!