I dont own the K-7, Ive had the K20D for the past year, so while ive followed all the talk around the k-7, there was no real reason for me to upgrade.
All I can say is that you will be more than happy with an upgrade of that size/generation. I went from the K100D to the K20D and was pretty amazed at the difference.
Paired with some good lenses its a killer camera.
Im still keeping my eye out for a water resistant 18-55mm to go with my k20d. ;) I love rain.