I really struggled with taking the big falls on the mat. On the crash pad is easy but on the mat was quite scary.
I crossed a major hurdle when I served as uke in a Shodan demonstration. The tori was about half my size and totally intimidated to throw me. Talking her through tossing me safely helped me a lot. However, the big change occured as the result of a complete fluke.
As we were finishing up the Ju Nana Hon no Kata, she did Hiki Otoshi (which can be quite intimidating to uke) on one side with no problem. On the other side, however, she lost her grip on my arm.
I didn't even think about it because I had plenty of momentum and the fall happened flawlessly. I did notice a few gasps from the gallery.
The more I thought about that experience, the more I realized that it's the combination of my skills in ukemi as well as the skills of my tori that make my falls safe. So long as I keep my ukemi sharp and make sure my tori is compitent and confident, I'll be taking falls for years to come.