I found the diablo to be the best boot that I had ever skied. I sized it short so I had to do some toe grinding. But when it was dialed in it was perfect. As I became a better racer, I began to overpower the flex. In free skiing it is the perfect flex. But for racing, I am 6' 4" tall and lever the boot to strongly in the course.
I am in the doberman now for racing and have the 150 flex. I also bought a second doberman and had it way softened for free sking. I just didn't want to be jumping back and forth between brands of boots outside the racecourse. I rave about the doberman in the course. I rave about the tecnica for free sking.
They are both great boots. The rest is determined by fit. Hope this helps.