I am concerning of the pixel quality since i am submitting to microstock that image quality is important. I am sure K7 is comparable to k10D/20D, but how is KX, that 2 year technology helps?
i think perhaps if you read more about microstock/stock photography you will realise that most dslrs have acceptable image quality.
what they are more concerned about tends to be noise, and whether you have overmanipulated it such that at high resolution the pixels have somewhat degraded. for example, if you submit a k-x image at iso3200, versus a k10d image at iso100, you bet they'd take the second over the first if they had to take one, all other things equal.
and of course, the nature of your images. stock images tend to be very.. typical, somehow. things that relate to advertising, things that fit in advertising. you are right that stock agencies do not tend to care much about whether an image is award winning, or whether the composition is great, they are looking out for certain things. i know friends who took up stock photography pretty seriously, some of them got in too deep, and it became a bit tiresome to hear them evaluating every image in relation to stock, e.g. "this image can be used for stock, and is nice, not bad", or "this image is bad, but a stock agency will have use for it so i will shoot it".
did they earn money? yes. but to me they didn't quite get sufficient renumeration for their effort. possibly because they used the stock agencies with less than satisfactory compensation. i won't know, what i saw was that stock photography tended to kill one's interest in photography for the things i held dear, so my advice for anyone who takes photography up as a hobby - if you do not need that extra income, try not to get too serious in stock photography. of course there are people who can maintain that balance and keep stock and hobby apart, but not everyone can do that, and that's something to think about.
even if you have a 6 megapixel image, i wager you can find a stock agency to take it, just that you won't be able to sell it at the higher end of reso if there is such an option.........?