EE armors have always been buggy for me, only working some of the time, or not providing the full 90% damage reduction. EE itself is not the most stable mod out there.
If i want to kill somebody in redmatter armor, all I would do is pull out my swift wolfs rending gale and use my autoclicker to spam the little green whirlwinds.
The autoclicker clicks about 100 times in a second, and with a slight server lag, all of those 100 little whirlwinds hits a player and stacks for height, sending them thousands of blocks straight up and down. Therefore killing them instantly. I believe one of the admins on my server tested the falling height of quantum armor, it is insanely high up. Could have been close to 10,000 blocks. And by that height you would get bored of falling and log off.