The point about Leaner Legs is endurance, and a constant tension on the muscles. Cathe never really stops, the rests are all active rests working opposing muscles. A good sub might be to combine the leg section of MIS followed immediately by the leg section of PH. That would run to about the same amount of time as Leaner Legs, the focus of those two videos is endurance mainly, and it would certainly keep the tension on.
Caveat: in both these videos Cathe uses a 40 pound barbell if I remember correctly, whereas in LL she uses 35 pounds. If you were to do the MIS + PH combo, I would take the barbell weight down to 35 pounds, or whatever you are comfortable with, since you will be going longer.
Another alternative would be to do PLB first 27 minutes of pyramid work only, this is also endurance. Or do PH plus all the leg work from Muscle Endurance, since it features a lot of different exercises that would compliment the PH work but not repeat the same (leg presses and glute raises I'm talking about here).
Whatever combo you do should work because LL really blasts the lower body, and any and all of these combos will too!
Have fun, or maybe not!
Clare