re: Rucking vest weight

I've never heard of a rucking vest, or no one calls it that, just weighted vests. There's rucksacks, which are backpacks. Then there are weighted vests and plate carriers. Depending on what you intend to do you will have to read about each style and decide for yourself.

If you just want to walk with weight. Rucksack works, weighted vest works, and plate carriers work.

If you want to do high intensity calisthenics (jumping of any kind, burpees, rolling around on the ground, etc) you'll want something less bulky and something that is capable of firmly staying in place on your body without shifting around a great deal, or you'll run the risk of catching a weighted plate in the base of your skull or maybe riding up and smacking you in your jaw, for example. In general, I can't say for sure if a weighted vest or a plate carrier is best for this kind of application without looking at it's features first.

You may not want any weight on your chest at all, so a vest of any kind is probably out, so you'd want a rucksack or a plate carrier with no front pocket. It all depends on use.