Quote: Also, there is a huge difference between "no advantage' and "an advantage seen in only certain situations... such as scenes of a certain dynamic range and photographed using suitably low ISO."
I'd like to see any photos demonstrating any advantage, anytime , anywhere, any DR, I don't care. If folks are going to say things like that, surely they should support them, I'm saying I haven't seen a difference, that's an absolute fact. I'm waiting for someone to show me the difference, something that contradicts my own shooting...
And yes it's pretty much irrelevant to the OP, so why did someone bring it up? The way fallacies get started on the internet is folks making unsupported statements in random conversations, which then get repeated as fact. As far as I can tell this is one of them.
To the OP, I'd say, a bargain K-30 will be just as good as any 14 bit engine, in any circumstance I've seen, and if you can save a few hundred more dollars for a tamron 90 or Sigma 70, whatever. If you can't find a bargain K-30 look at a K-5IIs.
Get a lens that's pretty much distortion free for reproducing your art. Something good edge to edge. EG the 35 2.8 macro has .4% distortion, the 35 2.4 .8% distortion, the Sigma 70 macro, .116% distortion, the Tamron 90 macro .161.
The distortion of both of the longer lenses is negligible. For reproducing anything, I'd go for the 70 macro, and buy the best body I could buy for it with the funds I have. The lens will make more difference than the camera body as long as you're buying K-30 though K-5Iis, the K-3 adds a level of sharpness you can't match with a 16 Mp camera, but that sensor used ion the K5- K-30, K-50, K-01, K5II. K-5IIs is no slouch. Get the lens you need, buy the camera that goes with it, the best you can afford, but of the 16mp cameras... the lens will make more difference than the camera body.
Incidently, also love what the Sigma 70 does as a portrait lens and a macro lens, although something like a 35 2.4. to go with it (the FA 50 1.4 is .35%, better than the 35s but not in 70-100 range) would be a good investment as well as an 18-135 for walking around.