VTrunner - You see, this is what confuses me a little about yours and Dan's subLT. Surely if it's SUB then by definition there should be no accumulation of Lactate and you should be able to maintain your pace in the marathon (all things equal).
Does it not make you wonder if your Threshold is actually at a lower HR/ slower pace than you think? HAAD's percentages are a guide and we must all be different.
Dan - Am I correct in thinking that if your recent Sub Lactate session averaged around 7.30 pace, then this is the minimum pace you would run your marathon (ideal being at, or just below LT), which predicts a 3.17 marathon ?