Isn't the LE capable of dual AC inputs? The 30A LOR systems are capable of dual power inputs and do use 14AWG for the input power cords and 18AWG for the outputs. From what I have been reading, 14AWG is what is rated for 15A, but there is a caveat. That rating is at 50C. At lower temperatures, the safe current carrying capacity should be greater than at the rated "room temp".
On the other hand, almost everything that my friend is running is LED with the exception of a few incandescent items.
So at .03A per 50-60 ct LED string, and assuming a max working load current of 3A on each of the 6A triacs, that is around 100 strings per channel, and that is probably unlikely. AT .3A per 100 ct incandescent, that is still 10 strings per channel, and I think that is probably unlikely as well.
So, assuming total amps at 30A for the unit, that would average out to around 2A per channel constant (60-70 LED strings or 5 incandescent strings per channel), but they probably won't be on constantly for long perionds of time. You are only looking at a surge of 30A for probably less than a second, and that should trip your GFCI anyway.
I have plenty of the 18AWG to 14AWG PC power cords from PCS, servers, an monitors. With ambient temps around 50F or lower during show times, this is only around 9C. This should allow some additional overhead as far as conductor overheating. This does not take into account any of the overhead that is built into the cable specs to begin with.
All I am saying is that there is a perfect paper recommendation, but also a practical, safe, and less expensive option as well.
I may still be wrong, but I will probably argue until my extension cord catches fire.
Oh, and if I am wrong about the dual AC input, then ignore what I just typed