I have a K10D and a K20D, and I am happy with hem both. The resolution and higher ISO performance on the K20D is much better than the K10D, but still not anywhere near Cankon's performance.
But they are as tough as old boots, heavy and full of features that I search for in vain on the odd occasion that I find myself using a Cankon of similar cost (5 frame bracketing, multiple exposure to name but two). In short I like them.
You do not need to have faster lenses, necessarily, to get a decent depth of field effect, although I have manged to get a 50mm f1.4 (an old F series lens) and a Tamron 90mm f2.8 into my camera bag.
This picture was taken with a Tamron 28-300 at f8, for example.
I think that realistically FF cameras will be beyond my means for the foreseeable future, so I'll make the most of the APS-Cs for now.