how did they handle compared to the m14 on full auto?
Slightly worse. Despite the more in-line recoil, more forward point of balance (muzzle heaviness), and pistol grip, the FAL's lesser weight made for a hard recoiling & muzzle climbing ride.
Which isn't saying much, because standard select fire M14s also sucked in full-auto mode. As did G3s.
The M14E2 was an improvement in full auto controllability over all three (FAL, M14, & G3), but sucked as well. Even when fired in aimed slow short bursts. It was also a hard recoiling piece.
I was issued both M14 w/ selector and the M14E2 versions at Old Scroll 2/75 Rangers. Later used the FAL & G3 at 18B Course, during numerous ODA training events or JCET exchanges with allied forces, as well as at various schools or range venues. This across several decades.
By way of comparison, during 2007/2008 unit testing and down range deployments to Iraq, I found the M17 SCAR-H to be subjectively more controllable (and objectively more accurate) during full auto fire. This despite it's lighter base weight. With the added weight of all the bells & whistles attached (optics, lasers, etc.), it just shot better than those previous battle rifles. Whether on semi or full auto.
In places like Iraq, Afghanistan, and Africa, I often encountered FALs (or G3s). But they were mostly regarded as curiosities unless a partner force was running them. Still guns to be respected, but generally not the armament of well-funded & equipped modern forces.
There's a reason the old M1918/1922 BAR was considered a very accurate and controllable auto-rifle. It had the required mass and massive action to tame full power .30 cartridges. Rifles like the M14, FAL, and G3... never did.
As with any marginally accurate weapon (e.g., shorty pistol grip shotguns), you can train yourself to become relatively effective with a select fire battle rifle. However, in the main, some shots are likely near climbing misses when fired as bursts. Most are very high misses when the trigger gets held back for longer strings. Especially so when fired from non-prone supported positions.
Most full auto battle rifles deliver a lot of noisy Sturm und Drang... but damn few hits compared to aimed & rapidly delivered semi-auto shots with the same weapons. Up close... they are devastating in effect and in generating momentary suppression. As long as you don't mind ventilating what's directly behind or laterally within the cone of fire to the target.
IMHO, FAL/G3/M14 select fire capability briefed well, but was mostly impracticable in real usage. Wasted ammo expended missing targets. Except at close range (<25 meters). Good more for delivering short suppressive bursts at distant point targets vs. actual hits.
YMMV.