I used to run SR-71's->DMIC-20->DA-p20 and it sounded great, was easy to run, etc.
I have 77's now but i never ran them into the dmic-20->da-p20, but overall i havent noticed a significant difference between the two. The 77's are more forgiving and flexible, pickup a little more bass, are a little clearer. You can find 71's now dirt cheap, around $300+, and they'd be the best used mic for the money around.
peace
Evan