IMO the identifications by witnesses Smith and McClusky, both based on the same TV footage, and both 4 months after their sightings, are simply two cases of mistaken identification by the transference phenomenon, not deliberate plotting of any kind.
But yes it makes sense that a perp would prefer to move something away from the crime scene in a concealed state, meaning inside some container along with something that it would be normal to remove. So even if there were onlookers they would not bat an eyelid.
I agree with the transference phenomenon given the coverage the Drs McCann and Madeleine were being given by the media. I think it encouraged a false memory syndrome which in conjunction with actual events became etched in the witnesses recall of events.
Studies have shown that memory is very fragile and malleable.
I also agree the perpetrator would prefer to move the child surreptitiously rather than carrying her openly. I think concealment in a laundry basket is one option. I think it is possible that initial concealment might have been in apartment 5J until an opportunity presented itself to make the move.
That scenario would imply a planned abduction rather than something which just happened ~ if she were drugged.
On the other hand ~ when one thinks of the trail followed by the GNR dogs ~ could Madeleine have walked hand in hand with her abductor to 5J ~ and the dogs later followed the perpetrator's scent to the car park where it was lost?