Pace, for sure.
BUT, the rider has his butt on the cantle and his feet on the dashboard. Do that right and you can get a warmblood to pace!!!
OK, that's an overstatement. But the way he's being ridden is pushing him to pace, no matter what his "native" gait might be. Right now, if I were interested, I'd be looking at sire, dam, and siblings. What kind of gaits are they showing at maturity. Also what, if any, physiological difficulties do his siblings show?
What's the asking price? Stallion or gelding?
War Story: I learned a hard, and expensive, lesson with blue roan gelding back in the early '90s. He was a looker and I got lost in his lovely color. I failed to notice the injuries he's sustained during his training as a Big Lick horse (he was the third horse I ever bought; I was greener than he was). He was three and half when I bought him for a premium price. Within six months I sold him as a pasture ornament at meat price because he was so lame under any kind of load.
1. The Big Lick process, even without soring, causes permanent damage to even a horse bred to the process.
2. A pacy horse is a project horse no matter how much you pay for it.
3. You can cover up a lot of problems in horses with drugs.
4. Ignore color and don't ignore conformation.
5. If your eye is not experienced then the PPE process is your friend.
Walk very carefully here.