Funny thing is...I don't remember the original game being that hard. Probably because it really didn't have any other levels beyond the easiest one. (Or something to that effect).
I played a terror mission back in January with a game date in January. Fortunately I over packed the Skyranger cause I was surprised to see not 2, not 3, not 4, but 6 cyberdiscs in play! I played desperate, pinging it with rifles down to emptying my spare clips in it. Went back to the ranger and grabbed the dusty rocket launchers and fired them to the best effect I could. Deployed every last one of my smoke grenades trying to get in close enough to damage them. Tossed every grenade at them I could muster. There is nothing worst than two cyberdiscs seemingly to work in tandem, let alone a third one that moved into location and openned fire unexpectedly. Hit one, the other spun off reaction fire...it was horrible for my poor young squaddies and rookies.
That mission ended up killing my young xcom commander, and my two best shooters. Much fun!