We used to call the jumperoo the "pooperoo" with our daughter, because no matter how long it had been since her last poop, jumping in there for ten minutes guaranteed a giant poop.
The seat of A's swing vibrates and yup. If she's in there for more than 10 mins its poop time. I actually used to use it to help her poop, before we figured out it was a formula sensativity.
Re: Bouncy chair benefits
Edit. Seat of seat? Really?
He outgrows it in like 2 more pounds