Uh, yeah, I would hold off on those 3000's if you depend on beam forming. Even though the new 4.5.# firmware is supposed fix the 3000's problems with beam forming I have found it's never a good idea bank your customer's happiness on firmware/fixes that don't exist yet and haven't been proven.
Also consider that the AC stuff needs about 3db more power than N so if you needed beam forming before you are going to need it even more with AC .