what would be wrong with one of the remington auto-loaders in 308 or 3006?
The most important characteristic of your defensive rifle, beyond either power or accuracy is reliability. Rifles based on military actions like the M-14 clones, the M-1 Garand, FN-49 etc probably have the best reputation for reliability although sporting rifles such as the BAR, and some of the new Euro gas guns by reputation are very good. I don't have any personal experience with this new breed. If you can get a Remington gas gun to function with 100% reliability, then it would be an equally good choice. Until a rifle, any rifle, can demonstrate 100% reliability under difficult conditions I would not choose it for protection.
In Canada, I would define difficult conditions as being out in conditions of high humidity and freezing temperatures with wind resulting in ice fog or freezing rain that without attention will cause the mechanical parts of the rifle to become ice covered. Dust and sand can pose serious problems as well, but this is normally a condition outside of the Canadian experience. If your rifle works under these conditions, then with reasonable attention to care and maintenance it will work on demand at any time. Any instance of failure to fire, failure to eject, or failure to feed should disqualify the rifle for use as a defensive arm, until the cause of that failure has been resolved.
This subject causes me to remember a day that polar bear came quite close during a lunch stop while on the coast. My Mossy 590 was propped against a nearby rock and when the dog took off for the bear, before we realized one was close by, he got tangled up in the sling and pulled the gun down into the soft beach sand. This resulted in some fast wiping and blowing, and a round could only be chambered with enthusiastic manipulation of the action, but it worked. I shudder to think what might of happened had that gun been an auto and the bear had been looking for a fight.