You can get your ECV when you change planes as long as you gate check it. You take it to the door of the plan with you, they take it from there and load it just like they do the strollers. Then when the plane lands they bring it to the door of the plane again and you go to your next flight and do it all over again.
If you check your ECV at the check in desk with your luggage then you won't see it again until the end of the trip, but I would never advise doing that. It is much safer and more convenient to keep it with you and gate check it.