pentax doesn't appear to have a front and rear curtain flash sync.
nikon and canons colors are a little different, but pentax's colors are a lot different! . . . well the more i look the more it seems like canons.
its noise looks to be slightly worse than both canon and nikons, especially over iso 640.
read the dp review, theres alot to it.
the edges of your images won't be as crisp as with the d80, but overall dp review says its about the same in the center of the image (image processer, so if you use adobe raw it fixes the problem)
a good thing to keep in mind is that even a 30d at 8mp's gets just as much detail . . . unless you use adobe raw with the k10d, but its not a big difference.