That is helpful. But whoever I send my ecash to has to redeem it for sats at the mint where the ecash was created right?
Yes, that's correct. When they redeem it, it will automatically add their mint to your wallet if you don't already have their mint in your list. Cashu.me Wallet provides a lightning swap feature to easily move ecash from one mint to another, or you can do it manually yourself, but it's a pain in the ass. The Cashu.me swap feature is easiest, most painless way to do it.