One point not made yet:
How anal are you about cleaning?
HK's...do NOT clean easily. Quite honestly, after 300 rounds...they're dirtier than any AR. Period. My HK93 gets so gunked up...it still functions, mind you, but holy crap, it takes close to 2 hours just to get the reciever in a condition I'd call "clean", and even then...it's not pristene. I've not pushed my HK past there...but I wouldn't want to, either. Too much gunk. Too dirty.
FALs, on the other hand, clean up in no time. Compared to an HK91, they run a far cleaner system. Most of your cleanup will be wiping off the oprod, swabbing the gas tube if you're so inclined, and swabbing down the bore. Everything else just wipes straight off.
FAL mags can be had for dirt cheap, as well as G3/HK91 mags.
I have an HK93...and I'm about to sell it. Just too dirty for me, and this is as a guy who has 4 different AR's. Those get dirty, but HK's get dirty like you wouldn't believe.
Just offering another viewpoint..