I tried shock cord for a little while, but found that after a few series of combat (out of battery) reloads, tactical reloads, speed feed reloads, and active firearm malfunction drills, the shock cord tends to fray away and soon the inner elastic is exposed. Failure of the inner elastic cords is close at hand by that point. Additionally, I prefer something to "drop away" during malfunction drills to prevent any obstructions when clearing the slide of my firearm (I suppose with an E2e, the size may not be as intrusive in the feed clearing process). Plus, a tap-rack drill is that much more easier. Unless, of course, the shock cord is carried in a "bungy" fashion with enough slack to work with.
But I concede that it does make for a very comfortable carry with the shock cord if you're not concerned with the particulars of armed carry/encounters. Another nice feature of shock cord is that it becomes compact (lengthwise) and tie knots suffice quite well without the use of cord locks.
I use 550 para cord, and sometimes 450 para cord for a lot of my gear when I go hiking/skiing/outdoor meddling. Thanks for posting those instructions tsg, I'm going to give it a shot. Sounds like it'll be very compact, yet sturdy.