I've had the honour of sitting on a Vivaldi lineage before and they trot was something else- it was back in the day before I'd ever even tried dressage (and used to showjumpers so rarely ever spent any time in trot!) and I couldn't ride one stride of the trot!
He looks absolutely stunning and like he has a very bright future ahead of him. I haven't followed your story with him, I'm guessing you bred him yourself? It must be an amazing feeling to ride him at last and that trot is something else!