Sorry, I used to call my flying club's 152 an acrobat when i first joined it.. just out of habbit ive corrected people like i was! :P
Acutally now that i think about it, I remember that the Ka-50 has shorter blades than other semi articulated rotors,so less strain is put on and also it doesn't have stubs like the AH-64 does.. it has wings which provide lift..
So totally going back on myself, the Ka-50 should be able to perform these, but not at the same rate a Lynx or BO-105 can. (these two examples can "backflip" from a hover, and have a high roll rate)
The Ka-50 would have to have a minimum speed at which it can perform the maneuver. The wings would have to be providing enough lift for it to go inverted without it putting too much strain on the rotor head, it would also have to have much wider turning circle becuase of this too.
eg, profile of a Lynx loop /barrelroll = o
profile of a Ka-50 loop/barrelroll = O
Sorry if i came across i bit snotty, no harm intended! :D