[kerowo]

Let's fix the terminology then. Blind defense is used when you think someone is stealing your blinds. If you get overly attached to your blinds you will start calling with crap like suited gappers when you won't have near enough people in the pot.

The only time you want to call a raise in the blinds to be HU with someone is:
If you think they are raising light AND have a hand that's good against their range.
If you have a quality hand that is good against anyone's hand range.
I suppose if the guy raising is 10/3 and can fold when he misses the flop, but you need pretty good reads for this and a lot of table time in.

I don't think you have the reads in either of your examples to feel really good about playing 79s to a raise HU.