I think I did not express myself clearly as I am also not completly sure about these things. I think the reason for using the talk test is the same for both S&S and the LCCJ plan.
But my take is that average HR might be higher with LCCJ even when passing the talk test because HR might not be perfectly correlated to fuel depletion. Ballistics might use up ATP/CP faster and give you less chance of replenishing them during the effort. The LCCJ might be different here. At least this is one possible conclusion one could draw from Pavels quote on LCCJs in Q&D.
Which leads to an interesting question: At which average HR could you pass the talk test during different exercises?
Running, cycling, climbing, rowing, hiking, swings, snatches, LCCJ, TGU, burpees, might all have a different threshold here.