Ref the rumble seat, I would consider the ages of the children, and how long two seats are needed.
For toddler twins you could keep swapping them seats to share the view, but you can't recline for naps.
With a newbie and toddler, you can use the car seat for baby, or you can forward face the toddler seat reclined with the footrest folded upwards to leave more space for the toddler.
With a toddler and preschooler, obviously both rear face, and upright only.you might not expect to use the rumbleseat all the time, so the rest of the time its just a great luxury single stroller. I would imagine it pushes very well, even with a chunky toddler in the rumble.
I would rather use a rumble than a buggy board. Having said that the piggy back board looks fab, and there's plenty of headroom for standing child.
Ds loves clicking the leg rest up himself and sitting with legs horizontal, or with his knees up in a v relaxed posture. I showed him how it reclines, he loved that and went all round two shops reclined not because he was sleepy but because he wanted to. Giggling.
He wasn't keen on the hood visor at first. I pointed out it was a bit like a spaceship house. He's ok with it now.