2.0 is a new major release with a redesign of the acl-merge function which is the function that converts the text config into information usable by the ACE switching engine.
If your config is huge and it takes a long time to do any modification to it, you should upgrade to 2.0.
If not, I would recommend to stay in A2(1.x) and upgrade to the new release A2(1.4)
Gilles.
