It seems you don't really understand pooled mining. That decision is STILL done at the pool level. The miner only chooses which port to mine at with the pool if they want to make a decision. The mining hardware and miners are completely and utterly controlled in what they mine by the pool they choose to mine at. The only time there is choice is with solo mining which hardly anyone has enough hardware to afford doing by themselves any more. p2pool mining offers a tiny bit of control but it's still mostly done by the overall pool design.
That's absolutely true, I don't really understand it.
So when a miner chooses which port to mine at with the pool because they want to make a decision, can that decision affect which version number a block uses? It sounds like the answer is NO, their only decision is which port they use, and everything about the block will be the same no matter who solves it.
This, I could believe, if blocks 414056 and 414072 had the same version number (since they were both made by the same pool, Slush). However, since those two blocks, made by the same pool, have different version numbers, I'm looking for an explanation. Do you think the Slush pool operator is randomly choosing what version numbers to put on the blocks it solves? I don't.
So I'm left thinking that the reason those two blocks have different version numbers is because of decisions made by two different people, each of whom wanted a different version number on the block. If that's true, is there a way they can prove that they are the person who made that choice, give then block that has the version number they wanted?