I own a Friesian. Not sure who told you they had smooth gaits. Lol. When I get on another horse, its always shocking to me how much easier the trot is to ride. I also live in Mississippi. Our summer heat and humidity are tough on my girl. Those you see who own one in Florida either have climate controlled barns or arenas or will be selling them soon. Florida is brutal on these horses and they don't fair well in that climate. During the summer, I can only ride very early mornings (before 8am) or late in the evening (after 6pm) and they have to be kept short. During summer months, we stall during the day with fans, and pasture the horses overnight. Even so, I will find her panting and sweating in her stall (IF she sweats!) Last summer she had to be on supplements for anhidrosis and allergies.
The canter is fun to ride, but not easy for most friesians. Her stamina is about 1/4 of what you'd see with a normal horse (granted she is older), but I hear its the same for most of the breed. I've been riding her typically 5 days a week for the past year, yet still, after about 25-30 min, I'm not gonna get much good work out of her.
Don't get me wrong. I love my horse to death and she is a favorite of nearly everyone at my barn. She is lovely to look at and has an amazing, easy going temperament. She LOVES her person (me) and would rather spend her days with people, than with the herd. She's VERY smart and I've never felt less than 100% safe with her. BUT...performance wise, it's a tough sell. I can't say I won't ever buy another, but since owning one, I can't say that I haven't been envious of other breeds and their ability.
"Horses are too spency!" - Mom