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.
I think its a matter of what you want out of your training. If you are going full blast full power full everything all the time in training, then that is not a smart way to train fighting do matter what you are training for. Even the elite level UFC guys train with controlled contact. That is what the heavy bag, thai pads, and focus mitts are for, full power impact training on a regular basis. A true full contact sparring session would only be for testing something and not for regular training. If you see anyone training on a regular basis with full power in sparring run away quickly. They do not understand the methodology of smart and healthy training for any level of fighting or competition.