Jesse -
You probably use much much better quality banana plus than I have experience with. I have memories of Monster banana plugs I used with Infinity RS-1 and their speaker-level crossover that left me thinking I would limit banana plug use for home theater only because they are so damn convenient.
I admit to having started a calculation on surface contact area for banana plugs [2*pi*r*h] vs spades [you need to assume a size for the "ring of contact" and calculate the area and multiply by 2, a larger ring would improve things, but the area would be 2*Pi*(Rout-Rin)^2], but soon got distracted by the music. All things considered, if I found a banana plug that could be successfully soldered to 8 gage wire and that were strong enuf to stay put, I suppose that would be the way to go.
:-)
Pepe