Loader is definately detectable and like every other 3rd party program can get you banned.
Taken from DavianV. Blizzard Technical Support Rep.
It is indeed considered a hack in our books. We consider any third-party program designed to affect the way that a Blizzard game interacts with Battle.net including seemingly harmless programs designed to make doing things easier, such as changing hotkeys a hack program. The use of any such program may result in the closure of the account tied to the usage of the program, or even the temporary or permanent banning of the CD key tied to that particular account.
There are no exceptions to this policy.