Took Steve's hint and tried some metcon after some heavy, low rep lifting (heavy for me, maybe not some; it's all relative).
Did some DL's at 260 and front squats at 145. Started at 5 and worked down to 3, then tried the "Helen" workout (400m, 21 KB swings, 12 pu's).
My time was very slow (18 min.) from the prior work, but the result was that I was wiped out like never before.
Conclusion: I can see how the Afterburn would be more effective with the heavy work thrown in.