I have octogonal wooden ones...
Yeah, the reason you don't want to learn with padding is because there are times you'll actually wrap them around you... but in order to do so the chain/rope section is the part you actually want to wrap around. You have to put the tip right on your arm so you don't bash yourself. If you don't, then the other half swings into part of you... that happens only a few times.
But yeah if you have padding on then, you'd still have to learn to do it without the padding as you won't be wearing any padding like that if you ever need to use them.
'Chucks are cool, and once I finally get back to my martial arts schoo, I'l be forced to learn them to acquire my black belt (along with the Staff and kamas). They're cool, and would be damn fun to impress people with. I'm always in awe in chuck demonstrations. And that in turn makes for one heck of an intimidation move.
Oh yeah back to that padding part. I suggest that you DO wear Head Gear. This'll save you from the brain damage Shokan speaks of. Chest pads aren't a bad idea either.