Yes, the H-53A/D has done full aerobatics, I have enjoyed these maneuvers myself. The control authority and flight envelope are quite inpressive on the Stallion. I do not know of any 53E doing approved aerobatics, mostly because aerobatics had passed from the must-do to the why-do catagory in the intervening time. The CH-53E (70,000 lbs) and its smaller predecessor, the H-53D (42 to 50000 lbs) are no slouches. They are very big, fully operational in every way, and unrivaled in their practical ability to be used in combat. In other words, it is not a circus trick when these aircraft go to war.
Big machines have problems all to themselves, mostly due to the issue of low frequency fuselage modes that can create problems, especially in helicopters, where exciting vibrations are plentiful.
The most massive helicopter ever is the Mi-12 or V-12, which had two Mi-10 rotor systems laterally displayed on strong pylons (that's two 115 foot rotors!) and 26,000 horsepower. Only a few were built, it is rumored that dynamic interactions prevented full development. The fuselage is about the size of a good sized airbus. I saw this in a museum in Russia, it is unbelievable.
here is a web site found with one yahoo search:
http://www.flying.no/mi12.htm
The practical Russian big bird is the Mi-26, which has a 105 foot rotor, and can carry about 20 metric tons of cargo for short distances. It is in full production, with over 200 built so far. I know the test pilot and designer of this bird, they are Gorgen Karapetyan (a Hero of the Soviet Union for his personal bravery at Chernobyl) and Marat Tischenko (now a professor at University of Maryland). The Mil team is a first class group. The Mi-26 does suffer a bit from the old Soviet way of qualifying aircraft, with short lives and relatively high maintenance, due to the abundant manpower and the little competition of the old days. Even so, the Mi-26 is impressive! Here is a web site that discusses the Mi-26 at some length:
http://www.fas.org/man/dod-101/sys/ac/row/mi-26.htm