The difference between 10MP and 14MP is not that great in terms of increased print size -- it is an incremental upgrade. Unless you are printing for exhibition I doubt it matters. (However, the jump from the K100D to the K20D is definitely significant.)

The live view to me is a bit of a toy. If the screen was articulated so it could work from various angles then it would be useful in place of a right-angle viewfinder add-on, but that is not the case.

The improvements in quality at low light levels seem very real from examples posted. If that is important to you there is a good reason to upgrade, since even the K100D is better than the K10D in that regard.

The Dynamic Range Enlargement gives the equivalent of 1 EV more, not 2, as I understand it.

In particular cases the intervalometer, in-camera RAW processing and autofocus correction may be what you need. I would like the fact it's generally quieter in operation.

Only you can decide if these factors are enough.

Also, going eBay rate from USA sellers is equivalent to £330 and that often includes freebies like memory cards. Still not cheap enough for me to bother upgrading.

One thing you might want to consider is the value of keeping a backup body.

That coot is great... the texture of the feathers, the water, everything. Lovely sharp image.

Nice shots, esp. the second which looks very crisp. And 100% crops? Yikes that's some good camera.

I like them but suspect they are not true HDR (from multiple exposures) but pseudo-HDR. All the stuff I've done is pseudo, and the following is the most extreme example, because the SF looking building called for it.