I think what you get for that $600 is not the same in both cases since it depends on what platform you're "invested" in, so to speak. I found out that for me, as an android user (phone and TF101), the services I had access to (and the quality of those services) turned out to be a significant part of the decision (in my case it's a standard android tablet vs. Amazon's tablet). I use Prime, Kindle, and Amazon MP3--and the general quality/stability of standard android platforms/apps is sketchy at best (whereas, on my gf's original Kindle Fire--which is lack-luster in terms of most everything, it's still stable when running all the amazon services--which one would expect).
I think, though, if Android tablets were worth much of anything on the "productivity" or "creation" side, it would be a no-brainer--standard tablet all the way. But for now, Android's advantages of being a wide and open-platform also work against it in that case--it's sooo difficult to ensure any amount of stability and user experience across devices.
I'm all for whatever people want to use, whether it's an ipad, kindle, android, etc.--but as I've transitioned through the various ones, Amazon's mostly-locked but partially-open platform is by far the most appealing since tablets are still content-consumption devices. Where, IMHO, Apple shows contempt for their users (or rather, contempt for their users to have freedom with their hardware, and they had to funnel everyone through iTunes, and still do to some extent), Amazon is more-lax, but still not as lax as the general Android market. But I think they all appeal to different populations of people, and I'm all for more options for everyone.
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