Originally posted by lesmore49 I would have a number of lenses that were of limited use.
Basically yes. It's the same story in Nikon or Canon land. They both have lots of lenses that are designed to fit their APS-C bodies but not their FF bodies.
All your existing lenses will mount on a Pentax FF, some will work 100% fine, others will just probably vignette to varying degrees (the precise amount of which will vary by focal length and aperture). There is a thread in the Lens section that shows how many APS-C Pentax lenses will likely perform on FF.
FWIW a lot of FF shooters keep a crop body around as a backup, and to take advantage of the strengths of crop - eg the 1.5 crop factor is handy for telephoto, crop bodies and lenses are generally lighter etc. It's no disaster to have both types of bodies and lenses around in your kit.