Am I alone in feeling that Canon has, perhaps, lost its way at the top end of the market, albeit temporarily ? The new top end models simply don't provide what I want. The EOS1DX is clearly a sports camera body, not a studio camera, and I resent Canon for trying to pretend that it is.
I've been with Canon now for years, having used their EOS film bodies before digital . Time spent with Nikon !DXs confirmed my view that Canon had far superior ergonomics, and five years ago, the Canon EOS1DS Mk III was a game changer. However, since then Canon seems to have lost touch with its professional customers. As a result, last year, I bought a Nikon ( D800E) which I currently run along side my Canon equipment. It is a fine camera. Nikon seems to have priced this camera very competitively indeed, and I gather that it is making large inroads into what should have been the preserve of the 5D3 market.
Now we're told that Canon have no intention of producing a higher MP camera until next year, and given Canon's habit of announcing cameras long before they actually become available, the reality could be some time after that. By which time the Nikon D4X will be out.
How frustrating. I want to stay with Canon, but they sure are making it difficult.
So what is wrong with your 1Ds3? Is it now suddenly not a good camera? Are your photos now suddenly bad? If you want super high MP, go medium format. So what's the problem?
Is there even such a thing as affordable medium format? Can get a Mamiya 645 for 500 euro, but the digital back and the lens cost a foot, a leg and the whole of the body and then some!
No, there isn't "affordable" medium format. But the OP clearly doesn't have his arguments together. The D800, whether a better camera or not, is being trounced by the 5D Mark III in sales. TROUNCED. So really, nobody gives a rat's behind about 36 MP vs 22 MP. Nikon doesn't even have any lenses that can take full advantage of the 36 MP resolution. The lens that comes to mind for that type of resolving power is Canon's 135 f/2L. Other than that, all moot points regarding DSLR and if none of it's good enough, go medium format, whether "affordable" or not.
Regarding the OP, all the professional landscape and architecture photogs I know don't have either a D800/E or 5D Mark III, as they shoot MF. If you want an amazing studio camera, then keep the 1Ds Mark III and quit complaining. None of the pro photogs I know ever complain about gear, EVER, so I'm guessing you're not a pro, but an enthusiast or amateur, which is fine, but that fact is obviously contributing to your misunderstandings.