I have two, one a year old and one a weanling. Both from the same mare who is herself quiet and easy....fwiw both of them are very friendly, easy going and brave. On the other hand, it is often really hard to tell much about how they will under saddle until you put them under saddle.
The '08 Quaterback colt I bred was just started undersaddle by his professional owner. Very quiet, WTC on a loose rein in large outdoor in five rides. She put 14 rides on him, then back out for the winter. Quantum Leap is still a stallion and will be presented at the Hanoverian approvals next year. He is out of my Baryshnikov/Raphael mare Bel Etrice, who is one of the most sensible gals on earth