Agreed 100% with Crab - except to add a subtle difference. If, as crab said, you are already established in a downwind hover then the hard bit is done and the helicopter doesn't care where the wind is coming from. If, however, you are making a downwind approach, and have not yet lost translational lift (you have 30+ kts AIRseped) this is where you can get yourself in trouble if you don't have HOGE performance. That's to say, during the earlier stages of the approach, with sufficient translational lift you have plenty of power margin and all feels normal, as ground speed decays at a normal rate, airspeed will be much less than an equivalent into wind approach and relatively early in the approach, perhaps 150-300 feet AGL you will be losing a big proportion of your translational lift. If you don't have HOGE performance, or dont realise you are downwind this is where it can get nasty. You start to sink with the loss of TX lift, instinctively pulling power to contain sink, engine reaches max deliverable power, your still sinking, raising collective, rpm decays, sink accelerates and you have settled with power with decaying RPM, which may well lead to VRS. If you have HOGE power this should not happen as you will have sufficient power to contain the sink... BUT VRS is still a distinct possibility if you don't spot your low AIRspeed and high ROD.