[vbezhenar]

Re-signing could be done automatically when you plug your iDevice (unless TTL is really short like 1 hour). App ID, hash could be changed easily as well.

[0x0]

If you change the app ID you start over with an empty app data directory, which is a bit of a hassle.

[mynameisvlad]

Well I presume the hash wouldn't change in between installs, just from user to user.