What’s everyone’s opinion on toddler reins. Love them, hate them? Good idea? Completely unnecessary?

If you used them which style and why? I’m trying to decide what do. My son is so speedy and I’ve just had a c-section so I’m not sure I can manage sprinting after him for a while but would like to go out with him still. Are they safe? I’m worried if it could do any damage developmentally by restricting him? Or even physically, I’ve read about dislocations?

Thanks in advance for your comments