I compete in [and judge at] competitions fought under a form of semi-contact continuous rules. The actual level of contact can vary a fair bit between weight categories. We wear shoes, and fairly minimal protective gear, so controlled contact can still sting a bit.
I find that's about as hard a level of contact as I'd want to participate in regularly. As a super-heavyweight 'controlled' contact works out as 'contact hard enough to leave pretty nasty bruises but unlikely to do serious injury', and that's fine for me. I've done a little full-contact sparring in the past [boxing], and while it was fine as an occasional thing, I wouldn't want to be doing it regularly.
I don't really see what competing full-contact would really add for me. Or at least I can't see the benefits being great enough to persuade me to do it regularly.