The only problem with HDD cameras is the spinning disc can fail to record if the camera is moved (violently!) during filming.
Happened to a friend of mine when filming a news piece, move the camera too quickly and it had lots of drop out. Seemed to be happening too often to be reliable.
I think that solid state cards are the way forward although P2 and SxS are comedy expensive at the moment, SD cards and CF are being used in consumer cameras and you can get some pretty high GB storage now.
The only problem with digital is storage but then you knew that ;-)
HTH
Ant