Since I have a good set set of lenses for my K20D, I was elated when I read that the K-01 had an excellent APS-C sensor and I could use the full image and full functionality of all my lenses - and not need OS/VR lenses. Sure, the K-01 body is on the large side - but below are the disadvantages of having a small mirrorless body.
After reading about the Nikon FT-1 adapter that allows SOME Nikon DSLR lenses to be used on Nikon Mirrorless cameras, I was ecstatic that I haven't invested in Nikon lenses.
Here are some quotes from
Extension Tubes, Bellows, Adapters - Nikon FT1 Mount Adapter (Tested) - SLRgear.com!
"The adapter . . is available now for around $200" - and it doesn't even have any glass in it ! So I've saved $200.
"Nikon warns that when attaching a lens weighing over 380 grams (around 13 oz), the user should not lift the camera / adapter / lens combination from the camera, as potential damage to the lens mount could result" - so I don't risk breaking my camera when using the 70-200 or 50-500.
" autofocus will work, where it will not work with lenses which are not AF-S compatible" - all my AF lenses work.
" the camera operates at the selected aperture, so if you are stopped down to ƒ/8, you may find the image quite dark, and a little difficult to focus, as there isn't the tight depth-of-field delineating where focus begins and ends. The solution for this is easy - just stop up to the widest aperture, focus, and then stop down to take the photograph." - no worries, I won't miss out on any action shots doing that !!!!