By MF, do you mean film or digital.
If digital, sorry, K5 is not close, though it does have better DR than many MF cameras at this point in time.
If its against film done with a flatbed scanner (Epson V500, Canon 9000F), yes, I think its a match even against 67. Don't know about lab scans though, since I eliminated that option from my mind due to costs. I shoot with a Mamiya RB 67
K5 offers more MP if you need cropping.
The noise is fantastically fine grained.
AF is significantly more decisive and faster.
If you want to compare images. Try the Imaging Resource site :
Imaging Resource "Comparometer" ™ Digital Camera Image Comparison Page