Here is comparison of Beta Pictoris and AU Microscopii:
http://astro.berkeley.edu/~kalas/dis.../aumicvis.html
The image has the same scale for both stars, so it seems AU Mic might be quite a lot more difficult than Beta Pictoris. It will most likely require a lot of experimentation to catch it since the sweet spot between oversaturating the star and picking out the disc will likely be different again in this case.