I always like to use easy to understand examples of stuff to demonstrate a point. Take a round pipe. Try to bend it. Maybe you can, maybe you can't, dependis on how strong and thick it is to begin with. Now squash that same pipe till it's flat and wide. Can you bend it now? If you can, it is much easier to bend pushing on the flat wide side than from pushing on one of it's now thin edges. Same as a saw blade. Wobbles back and forth from side to side when you wave it in the air, yet it is strong enough to cut vertically to support itself while cutting through the tree, with the sides of the tree as you cut keeping the blade from bending.
Take that example and pull on the pipe instead of trying to bend it. If the pipe is oval or a circle it doesn't matter. You aren't trying to bend the spokes you pull on them.
Cross sectional area is when you slice the material 90deg from it's length. If you take the area of a DT Aerolite and a DT Revolution it will be the same. For that matter if you were to weigh the two (providing they are the same length) they will weigh the same as well. You are dealing with the same amount of material that is resisting being pulled apart. Since the material used is the same, the properties of stiffness will be the same.
Hope that helps.
Yes, I get that... pulling end to end is the same, and at a 90 degree cross section, the cross sectional area is the same as well. But cross sectional area cannot be talked about without talking about the angle which it is being derived from, that angle is an integral part of what defines "cross sectional area", right? We're probably getting into uber nerd territory now, but the concept is interesting. So, even though pulling the spoke end to end is the same whether a Revolution or an Aerolite is in question, the aerolite would sway a lot more in one direction than the other if your were to wave it about, whereas the revolution would sway the same no matter what angle it was being swayed from. In a perfect world with no lateral forces, then no issues. In fact, the aerolite would be better simply due to it's aerodynamic properties in the plane it's travelling. But when you start swaying the bike from side to side lateral forces come into play (or do they?), and the round spokes are thicker in that directional plane. At least, that's how I look at it. I may be wrong here, because I do see where you're coming from as well, that there are only pulling forces on the spoke involved, all else being equal. But I have to say, wheels I ride built with round spokes just seem more solid to me than wheels built with aero spokes. Maybe if I get a chance I'll build some identical wheels except for the spokes and try it out sometime as my own little experiment.
Thanks, interesting discussion and sorry I've kinda forgotten what the OP's original question even was, but I'm sure he's quite bored with it now...