I'm a Pentax user with some half decent lenses and a K-5 (and a couple of lesser bodies). In many ways that camera exceeds my skills by far, but over the time I've been getting more and more frustrated with its randomly working AF. Also, Pentax isn't making a full frame camera body, which I have been lusting for for a long time. I know there are once again rumors about a coming FF Pentax, but so far they are just that. Also, even if Pentax released such a camera, I'm afraid they'd either mess or overprice it. So I feel the time to buy into another brand is near, either to replace my current system or on the side.
Most of all I'm tempted by Nikon. I feel the IQ, including high ISO is excellent and Nikon also makes no-nonsense high quality bodies. The D800 and D800E are probably above what I'm willing to invest. The rumored D600 sounds interesting, but I get the feeling it'll be a cheaper lower quality option (if it'll be released at all). Worried that there might be some shortcomings or omissions in the design too.
But then there's the old warhorse D700. The price is coming down (to some 1560€ from a reputable store today). I think all the possible bugs and problems have been ironed out long ago. The camera is still capable of producing excellent pictures and has a good AF system. OK, 12 Mpix may not leave much space for heavy cropping and there's no video. But otherwise it's still a good buy.
Or is it? Of course it might be wise to wait and see of the D600 becomes reality, but by the time it'd be really available, the D700 may not be available new that readily any more. What do you think?