Has anyone done a cross like this and if so what did you think?

I'm just guessing here since I don't have much DTF experience but I would guess that would be a fairly sensitive horse with a lot of go.  I'd ride one just to see if I could get by them but I like forward moving sensitive horses.  I would hope it would be athletic as all get out as well.

I have zero experience with DTF. I have a lot of experience with Freckles Playboy horses and especially the mares. 

As far as cow horses go Freckles Playboy is still a producer and in the top 20 but mostly on the maternal side. Like said above, sensitive. And they are later maturing, something to consider if your looking at futurities. Most Freckles Playboy horses I've ridden and owned didn't hit their prime until derby/aged event/$$$ years.

Freckles Playboy will improve even the worst bloodlines.