I do think it's too easy to do it the Wrong Way, but I've easily migrated from phone to phone several times now with both techniques and think they alright. Si

I do think it's too easy to do it the Wrong Way, but I've easily migrated from phone to phone several times now with both techniques and think they alright. Signal presents both a "create account" or a "migrate account" option on a fresh install, which seems like the best compromise for UX flow. Also, considering their guarantee is to keep your messages secure, of course you need your old phone. If you wipe your phone that securely contains all your old messages they are gone. That is security. That said, if you have the backup of your messages and the code, then the developers might be able to debug what caused the migrations to fail if you submit a bug.