I love the machine. It's been with me for 3 years and has been 100% reliable. The double wall SS drum produces consistent, even roasts and you don't even start wetting your pants if you decide to go for a french or Vienna roast (although a squirt bottle of water and a real extinguisher should always be near at hand just in case). It's double vented to the outside, one for the roasting chamber and 1 for the cooling tray so your space stays smoke free with just the aroma of the coffee after its been cooled and you shut off the cooling fans. Frankly, there's not a better smell on this planet than the aroma of a nice pipe of tobacco and the roaster going at the same time. I LOVE roasting days.... sigh. But I digress......
The hottop and BC are very similar in function except the Hottop is electric and fully automatic (or manual if you choose), and the BC is gas and manual.
The Hottop has a cooling tray that sucks air our of the finished roast quite efficiently. Your beans will hit room temp in about 2 minutes with its system. Obviously, so does the BC.
If you plan on roasting hard core as a boutique business or have a fan base to keep supplied, I think the BC is the best roaster you can buy under 10 grand. The Hottop is awesome for personal use and is the best machine you can buy under 2 grand to be sure. It's fully programmable and if you record a roast that turns out perfect, you can just start that roast anytime and it will repeat the profile; changing temps, ROR, drum speeds, durations, and finally drop your roast all automatically. It's a great machine!
YOMV...
Sorry for the diarrhea of the mouth.... If you get me talking about one of my hobbies it's hard to shut me up!!!