I tried my Thermoworks Billows on my B series today. I did some back ribs. Weather here today was terrible - very rainy.
The cook turned out really well - Billows was easy to use with the mounting plates. I had to drill two holes into my bottom vent grate to allow for the spring to clamp correctly. I also had to cut the mounting plate slightly to fit the groove of the bottom vent. Top vent was open very little as instructed and didn't touch for the whole cook.
It did keep the temp very steady - although still saw spikes when opening and closing the lid. Which I only did 3 times - ribs on, wrap and back on to sauce. Thermoworks said it's supposed to account for lid opening in its most recent firmware release, but can still see a bit of over compensation by Signals/Billows.
I have had Signals since early last year, not sure I would invest in the Signals just to get Billows. That said, Signals is awesome on its own. I can generally regulate nearly as well through usually methods. I believe the value will be in the over night cooks and reduced stress about not having to worry about drops or spikes.
225 degrees, Jealous Devil Charcoal, Sugar Maple for the smoke. 3-2-.5 timing on the ribs.
Went searching for a replacement probe for my ChefAlarm and discovered that thermoworks has a sale running on their website until August 28. 15% off - it's not a huge discount but if you were already thinking of getting something it's a good time to pull the trigger. All of their products tend to get very positive reviews from what I've seen.
www.thermoworks.com - promo code is announced everywhere on the site: SITEWIDE15
Thermoworks must have a boat load of their older single time timesticks. They're running a special that if you buy $99 worth of stuff they'll send you a free single time timestick.