Post this on the Disabilities board to get more replies, but I will say that I have flown often with my CPAP and have never had any problems (I have three relatives with them, too, who have all flown with them). DEFINATELY take it as carry on (too valuable to have checked), I have never had it counted as one of my carryons (same as any other medical equipment). My bag for it is not very padded, so I put it under the seat in front of me, rather than jam it in the overhead compartment and risk getting it banged around. Consider taking extras of the disposable parts (filters, nose piece, etc), and a small roll of duct tape (in case of last minute repair). Good luck and have a great trip!
Terri