Well, what specialized equipment you need for cavern diving depends in part on how you view diving in an overhead environment.
At the very least, you need to own and know how to use a reel, and at least one spool. The most basic concept of diving in an overhead environment is that you need to be able to get OUT (anybody can get IN) and OUT may require finding your way there in drastically reduced visibility, or in the dark.
Another characteristic of cavern diving is that in many cases, the surface is not a reasonable option to solve problems. You have to solve whatever issue you have where you are, and that includes gas loss like freeflows or leaks. Therefore, most people believe that you should have some kind of true redundancy. Some agencies teach cavern in a single tank, but I believe they all require an H valve, so that you have two first stages (I could be wrong on this). That still leaves your tank o-ring as a single source of catastrophic failure, but tank o-rings fail pretty rarely during a dive.
A lot of people believe that you should not be diving in any overhead environment bigger than a simple swim-through without true redundancy in the form of double tanks, either backmounted and manifolded, or sidemounted.
Like all diving, diving in the overhead is delightfully simple, right up until it is not. But when you get in trouble in the overhead, you are in very real trouble. Thus the training, and the differences in equipment.
Is it dangerous? Well, the risks are higher than doing 60 foot reef dives. If you are properly trained, properly equipped and have an appropriately respectful approach to what you are doing, the risks may well be acceptable to you. They are to me!