I am probably just a klutz, but even prying the seal off with an xacto knife, I usually crimp it, which leaves it open to contamination.

So to summarize. The original question was: "Sealed hub bearings: to replace or not to replace?"

Some would say, You may damage them when you take them apart; you can never get them really clean because you can't dismantle them all the way; there may be wear in the bearing parts or the seals that you can not see; and replacement cartridges are cheap, so why not just replace them?

Others say, With a small amount of work, you can get a lot more life out them with no perceptible decrease in performance, and that can be pretty satisfying by itself. Even in the worst case, catastrophic failure is not a real risk.

So I guess the answer to your question is "Yes".