DD used an amby in her nursery at daycare up until she was a little over 12 months old! so they can do the long haul if your bubs likes them.

I really liked that they were sturdy and also DD did great sleeps in them as when a sleep cycle ended and she was in a light sleep the gentle rocking that happened as a result of her movement usually sent her back to sleep. one well rested bubba!

have you thought about maybe hiring one at first (there are quite a few places that hire them if you search on google)? i just say this because they are exxy and not all bubbas are too keen on them...just a thought though..