I'm on my second baby and I haven't found either of them remotely portable. Both have been extremely susceptible to overtiredness and would scream the place down if you missed their sleep cues. My eldest would only nap in his cot in a dark room so he wasn't portable at all - wouldn't sleep in the carrier, pram or car seat. My youngest (12 weeks) will ONLY contact nap so you'd think he would be more portable as he sleeps in the sling but he will not entertain being in the sling between naps - tries to fling himself out and screams his head off. And hates the pram. And hates the car seat. If we do go out I have to put up with him screaming between naps and then lug my gigantic boobs out to try to feed him while he flails about and refuses to latch on.
Who are these unicorn portable babies? I was under the impression from impassioned babywearers that newborns just sit contentedly in the sling all day between peacefully dropping off for naps. Nope.