mono
There are several a/c flying with them installed for evaluation & proving.
This is not correct, Airbus has full certification for the modification and will shortly also have it with the A319 & A321.
I believe all A320FAM aircraft now being delivered have the wing modification (provision for Sharklets) embodied. It is an option at the moment on the A320 to install the Sharklets, however not on the A321 until certification has been completed.