No both are rebuildable, and Auburns are actually easier to rebuild, I have done one before, and the Auburn is pretty cheap to rebuild. I did one on my 95 Mustang GT, and it cost me $85, for the conical clutches. I ordered it from Auburn direct, and it included the instructions for the rebuild. You need an aircompressor and air clamp to compress the spring, that is the only catch, and you can do it while it is in the vehicle!
The Eaton's I heard are about $180 to $220 to rebuild, since they have to be pulled out to rebuild.

 

No problems with my Auburn Pro. Had it even when I was juiced.