You won't notice any particular change required in the way you fly, but the rigid head (found only in the BO-105 / BK117 in the civil market as far as I know) will have much more 'crisp' response to control inputs. The down side to that is that the ride quality in turbulence suffers from being a bit uncomfortable for some people.
One major difference you would note is that off-level landings in a rigid head require that the cyclic not be moved, and that you pay attention to the mast bending moment gage. (easy to do off-level landings though, just a different technique)
Coming from a teetering rotor background? You'll notice that it is easier to hover precisely in either one, but at the slight expense of having to pay more attention to the machine in the cruise in some conditions.
At high altitude, with both (non-teetering) rotor head types you can expect some cross-coupling of control inputs due to Locke number effects - i.e. a pitch input will show up as a slight roll input as well.