I've got a Primo XL and an Akorn. To keep it short, the ceramic Primo is easier to hold temps. Sure the Primo (or any ceramic cooker) is more $, but for me the Primo is a more solid choice.
The Akorn is good, but ask me 2-3 years how its holding up and .....
The Primo? I know it will be exactly the same as it is right now. Same as any other ceramic I guess. Just my opinion :)
2 WSM 18.5"
Blazing Blue Thermapen
BBQ Guru DigiQ DX2