My experience has been that the outer bearing goes dry sooner than the inner. I figure that it goes around just as many times as the inner but has less grease.

If the rollers or either race is at all rough, they should be replaced. Discoloration can be a little bit of a judgement call, but clearly a bad sign too. A little looseness on the inner race is not always an immediate fail.

It is good to keep wearing parts as a matched set. Install the new outer race if you replace the bearing.

Greg