Insuring BJ

I'm sure this has been discussed previously, but when is it
appropriate to take even money when you're dealt a blackjack?
Recently I was dealt a BJ on a moderately positive count, and
I would normally have insured the hand. After all, I figured
it was more likely than not that the dealer had a 10 beneath
her ace, and I didn't want my BJ to go for naught. Am I missing
something here? Thanks in advance.

Curious George