With a passenger in the centre seat, you may not be able to reach and open the auxiliary air inlet, should the particle sep become blocked with ice/snow. I don't believe it has anything to do with CofG. I've had it flame-out & relight while in straight and level while slinging. The a/c was no more nosedown than in normal flight.
If you do want to fly in falling snow, get ahold of a proper snow deflector. That way there's no flameout problems.
Make absolute sure that your skids are clear, and free from the ground before you start up. With an R22 take hold of the T/R gearbox, and pull down. It should go down with reasonable ease. Our engineer said that the force needed to lift the skids will not harm the tailboom or it's attachment. The same goes for the 500 series. Pull down on the tail, until both skids squat, then lift it back up.
If you don't have experience in snow that is deeper than ankle deep, I recommend you get instruction (try a holiday to Canada, or Switzerland where they get snow)!!! It is very easy to put the a/c into dynamic rollover if you aren't very careful. If you've shut down, get out and remove the snow from around the skids, to check to make sure the skids are clear. It's best if you can give yourself something to use as a reference. A stake, or clearing a spot right down to the ground. Be easy on the controls, and once clear of the surface, get out of the snowball quickly.
There is a good saying that may help. "If in doubt, don't".