Matt,
For me the 10 round split between Dallas National and Whispering Pines would 6-4 either way or 5-5. I'm not on the fence, just indifferent. They are totally different courses, and as many have said, both are among the best the state has to offer. For perspective, I consider Whispering Pines to be superior to the Nicklaus course at Carlton Woods.
If given a choice I would rather spend a day at Wolf Point, Brookhollow, or Champions for reasons architectural and otherwise.
Wyatt