Let me give it a shot and jump in while here.
I have been looking at many C30 recently. I love the boat and am really getting interested in making a purchase. I have visited and examined MKI (79, 81, 82) and MKIII (95). I am 6 foot tall and not at all comfortable at ducking in the cabin. Since I am retired and looking forward at spending many days at a time aboard, I need a minimum of headroom. The MKI I visited were fine in the main cabin, just even in the galley (head rubbing) and too low about everywhere else. I can cope with that as long as I get some headroom where it matters the most and one bed long enough for me and wide enough the admiral and I.
However, the older boats I visited were needing too much TLC for what I was prepared to give, so I went for a younger boat, a 95 MKIII. Strangely enough, it did not have the headroom I was expecting in the main cabin. And matters got even worse everywhere else... It was a no-no for me.
So, here is the help I need from you folks owners of C30. At what year did Catalina change it's design and reduced headroom in its boats? I find that decision counterintuitive since people are getting taller and taller (my son sure is proof of that...).