I actually find the K30 to be sharper and have less noise in certain situations. Sure the k5, k5II and K5iis have 14bit which is slightly better for dynamic range, but I think in terms of sharpness, k30 seems better. For higher iso's 3200 and above, it seems the k5 variants have lower noise, but iso's that high are rarely used anyway. Check out the comparison images at imaging resource. I had heard somewhere that it was possible the K30 is sharpening or removing noise even from RAW files, while the K5 variants have a more raw, raw file.
Here are some (k5ii-s on left, k30 on right) @ iso 800