I'm terrible so I'm not much to judge, but of the three I've done - CEA on the MCC, and 3 and 4 back on the 360 - CEA was the hardest by far for me, even with Bandanna on. I was actually a little surprised 3 and 4 weren't harder than they were, except for a few choke points here and there.
I've never had the nerve to try 2 on Legendary yet, very intimidated by it from all the horror stories I've heard. I will at some point, but since I suck, it will be with Scarab on, for sure.
I actually felt Reach was pretty tough even on Heroic - Elites spam evade so much I find it hard to tag them with the noob combo.