I don't have a ProTemp Breezo, so I can't offer any thoughts there.
I do have a Thermoworks Bilows I've run with a Smoke X4 as well as a Pitmaster IQ - I prefer to use the Pitmaster IQ with my 18" WSM, for the following reasons.
1) The Pitmaster is equipped with an adjustable inlet damper, while the stock Billows inlet is wide open. Even without the fan running, I found that too much air would get by stationary Billows fan to keep the temperature under control. If you end up buying the Billows, be sure get the optional (at additional cost) adjustable damper, or you will struggle to control your WSM's temperature.
2) The Pitmaster controller controls a variable speed fan, which allows better temperature control by being able to vary the fan's speed. To the best of my knowledge, the Billows is only a single speed fan, meaning either full blast or full off for temperature control.
3) I don't know what the control algorithm is for the Billows, but I understand the Pitmaster controller to be a full PID (Proportional–Integral–Derivative) controller. That may be more technical than you want to get, but suffice it to say that a properly implemented PID controller can be expected to provide much better control than a simple thermostatic, or on-off control.
One other thought, and that is in regards to control by a cloud server. Both the Thermoworks Billows as well as the Pitmaster IQ are controlled locally, and don't require an Internet connection for proper operation. Beware of any products that require Internet connectivity for proper operation, as Internet connections can fail, or worse, the company goes out of business and their control servers go dark. Not saying that the Breezo operates in this manner, but just something to confirm before making a purchase of any product.
