What's the difference between the Ironman and the Revolution, and which do you prefer?

When they're folded, how much space would you say they take up?

When did you start using your Bob with LO?

Also, what would you say a good price for a second hand one is? I'm seeing prices ranging from $165 to $250.

Thanks ladies
ETA that we already have an every day stroller (UB vista) that's great for walks, so this would primarily be for runs.