My Friend burned out his Dewalt 18 volt drill last week turning his 6" Nils auger. After replacing the drill he plans on getting the Clam Ice Auger Conversion Kit. It is designed to take the stress through an industrial bearing and save the drill.
Parked a few times at Dave's place (Family Ice Cabins). He and his boys are the nicest people you'll ever meet. Very helpful and knowledgeable, highly recommend you see him especially if you are new to the ice.
After a lot of research, I recently bought the Elite-4 and the PPP-18i ice pack.
I am pretty sure if you already have the ice-ducer from the X67C it can be used with the Elite-4 but you will need an adapter to plug it in.
Had Michelin x-ice2s and they worked well on ice and okay in deep snow. Just got the Yokohama IG52Cs on my Civic. Been told they are as good as the x-ice but about $100 cheaper (for 4) than the michelins.