then use double-spends to pay out to those of us mining with them more than they could have legitimately mined, and they could do this for $X/50 blocks worth of time.
The ability to double-spend on the Bitcoin network is a bit of a misnomer, and it sounds like you have gotten the wrong idea because of that. You can only double-spend on the Bitcoin network to the extent that you can
temporarily fool two or more Bitcoin clients into accepting transactions that aren't actually valid, because the coins used in those transactions were spent elsewhere. This is only temporary, and eventually all but one of those conflicting transactions will be found invalid.
So, you can't create money with a double-spend attack; only trick people temporarily.
That site was worth taking down
No, it wasn't, and neither is any website "worth taking down." The internet is a means by which
all information is allowed to freely flow from one willing entity to the next, no matter how offensive people may deem that information to be.
Many people, it seems, for some reason think that being in the largest pool and paying largest fees somehow improves their chances. Kudos to deepbit for taxing their ignorance.
I don't know what other people's motivations are, but I personally use a pool because it provides a convenient means of knowing that my miners are working, and how much they are earning. With solo mining, how are you supposed to know your miners haven't gone offline? You can set up your own pushpool or mining proxy, but I'd rather spend my free time working on the open source FPGA project.
While we're on the subject, perhaps someone can help me understand one aspect of solo mining I haven't had the chance to personally explore. If your 95% probability solo mining time is >2 weeks, for example, will the difficulty changes ultimately have an adverse effect on your income? Statistics was never my strong suit.