Dont quote me on this but pretty sure that last part is incorrect. An unlocked phone/tablet will stay unlocked, inserting a sim will not lock the device. So long as you buy an unlocked one, yes you can swap freely between any carrier that supports the device.
This for sure...
Thanks for the correction guys. Glad people with more knowledge got the right info to BF!
It did lead me to wondering what the heck I had read that gave me that idea. I came across something to look out for BF:
Apparently there is something out there called “sim-free” phones and these do lock to first carrier used. Seems Apple is the only store where you can buy a truly unlocked phone.
https://discussions.apple.com/thread/5073470
https://discussions.apple.com/thread/4747669
https://discussions.apple.com/message/22819420#22819420
Not sure how reliable this info is, or if it applies to ipads. Maybe Comp or Bfillmaff know? I’m planning on getting a new phone this year and after finding this out today I will make sure to get it at the Apple store-just to be sure.