In reply to andrzej kierzek:
I wouldn't worry - there is stalking carried out by the estate, but I've never known it to cause problems for accessing the Dubh loch crags or surrounding tops. There's some decent camping spots at the top of the loch. There's currently road closures happening when the car park in Glen Muick fills up due to idiotic verge parking, but by Sept I'd expect that to no longer be necessary (hopefully!). The carpark is pay and display.
If you're worried give the Balmoral Estate Office a call.
Cheers,
STu