I do not specefically have the -56, but I own a MAS 49, Syrian contract piece. Very accurate, the unitized trigger group is a joy to clean, (One screw, toss it in a coffee cup full of solvent..)
The rear peep on the -56 is larger, and more field useable than the earlier MAS 49's, but for pure range work, it suffers..
Disadvantages? Ammo. Good frog 7.5 is very scarce, I do NOT reccomend handloading for the 49, or the 49/56 as they have an annoying tendency to turn full auto with even the hardest U.S. primers..(The firing pin is not sprung, nor is it exactily light..)
You WILL catch crap from the other battle rifle afficianados.. Til you hold nice one inch groups at 250 yards, prone.. (the 49, will do this..)
Supposedly a Portugese company is making very nice 7.5 for U.S. sales.. I have yet to see it personally..
In truth though, unless its REALLY cheap (200.00 with ALL the junk like spare mags, etc..) I would not reccomend it, as you'll get frustrated trying to regularly shoot it..
Meplat-