I have a PTR Squad carbine with a 16 inch fluted barrel AND a rail welded on from the factory.
http://ptr91.com/products/PTR%2091%20SC?id=9
It was worth the few extra dollars. I removed the rails from the hand guard because I did not really need them.You are not losing much with the short barrel, it is after all a battle rifle not a precision gun. That being said she is more accurate than I expected, will eat anything I feed her, though I do shy from steel when I can. Mags are cheap, parts are cheap and you can do most changes to it yourself.
The trigger does suck and the paddle release is a grand upgrade. As for optics I am running an ACOG on mine and its perfect, but if you are going to scope it you will want a cheek riser of some kind. I believe HKparts has one that snaps on for like 50 bucks. Parts are easy to find and relatively cheap, I ordered a MILspec stock from RTG and it came with a buffer and a sling, mags are also super cheap.
The one thing I do hate about my PTR is that it gets dirty, she will run like a clock, but you have to clean it sometime.
The other down side is that it is so freaking fun to shoot, you will want to shoot it all the time.
Regarding the FAL, well some of the advantages are:
Bolt hold open on last round
7 gas settings- a big deal with suppressors or shitty ammo
just as durable and cleaner - You will appreciate a piston system the first time you clean a delayed blow back
DSA has a reliable optic rail ( I have the carbine with another ACOG)
Better ERGOs in comparison
Neither one is sub MOA but if you have to reach out and engage a threat you can do it with confidence.
Hope this helps