Wow, I'm jealous that your kids would be in a sling! I tried it several times in different positions and all I got was screaming.

He wanted to be upright and moving, but not confined. So, for me, that just meant carrying him with my arms. He was 9lbs5oz at birth and grew quickly so I just remember most of that first year as being soar and overheated. He would do OK in the stroller or car seat as long as we were moving, but as soon as the car or stroller stopped, watch out!

And ditto on the "horizontal sensor" DH would have to walk DS for several hours each night before he was completely asleep adn could be put down.