Few points to bring up:
1. My local FAL gunsmith (former military armorer) said he does not recommend a barrel length less than 20" on a rifle with the standard-length gas system
and standard-size gas port.
If you want to go lower and still retain reliability of the gas system, a gunsmith must increase the diameter of the gas port in the barrel. I don't know how much this would cost.
Guns-Combat Annual did a report on the DSA rifle & carbine:
http://www.dsarms.com/ca_article.htm
They reported that the muzzle blast from a 16.25" barrel is excessive, and they would recommend a 18" barrel.
2. I disagree with Pthfndr with regard to the muzzle brake. I had the 3-hole DSA muzzle brake installed and I could easily notice the difference in felt recoil. The DSA brake is 3" long, but only adds about 1.5" to the overall length due to overlap. IMO, the muzzle report is louder for people observing compared to that heard by the shooter.
3. For the standard contour barrel, the difference in mass for a few inches of metal is minimal - a small fraction of a pound.
4. The standard length barrel is 22". The FAL is a pretty long design, and a 22" barrel + muzzle brake is
really long.
Just for handy-ness, I suggest a barrel length between 18" and 20".
5. A shorter barrel will not affect accuracy. It will reduce the muzzle velocity a bit - I've heard about 15-40 fps / inch. In my opinion, the handyness of a shorter barrel vastly outweighs the velocity loss.
How likely is it that you'll be shooting far enough with this particular rifle that the energy difference will make difference?
Also consider that at distances that a longer barrel's higher velocity would have a noticeable advantage (say, 1000 yards), a bigger facter will be your shooting skill, your sighting system (optics), and the accuracy of the rifle itself.
However, I would definitely consider a longer barrel on a precision bolt rifle.
6. Furniture: Consider your US parts count. I don't know of any US-made wood furniture that is currently shipping. DSA sells US-made handguards, pistol grip, and buttstock, all of which would towards the US-parts count. I personally like the plastic furniture, for the "black rifle" look, and weight.
7. front sight. My gunsmith recommended a dab of florescent nail polish, of all things.
-z