Recently I have found for softer, less dense Brazils I often have tipping and the profiles cannot be kept consistent, especially on subsequent roasts. Then it dawned on me it is the initial drum temperature, not the BT or ET, that has the greatest effect on tipping and a consistent starting point for the roast.
So I got a Fluke 561 infrared thermometer to monitor the drum temperature. Now the roast profiles are more consistent and reproducible.
BellaTaiwan did not respond to my inquiry when I first e-mailed in English. It took me a few months to learn how to type in Chinese, and voila, Jet, the proprietor, answered immediately. He did make it very clear that he can ship parts and instructions should I need any, but for all maintenance and service issues, I am on my own. The roaster is all manual, with minimal electronic parts, and from appearance, the motors for blower, drum, stirrer, thermocouple readouts, etc, can be sourced here in US. It does not have any type of automatic profiler to speak of, and definitely does not have the capability to translate the profile like from a small IR1 to the larger Diedrich. Built wise, it is actually less complicated than the HotTop. Because of its (relative) small size and full manual control, it should serve as an excellent sample roaster in a pro shop.
I have been thinking about the cast iron vs stainless drum a bit; ie the Mini 500 vs HotTop drums. The only analogy is pan or deep frying with cast iron vs stainless steel pan. Meat browning, also a Maillard reaction, is more prominent in a cast iron pan. How this material difference translates to coffee roasting, I do not know.
From several blogs, Feima the manufacturer in Taiwan does have a good reputation. In one blog the owner mentioned the manufacturer sent a technician on a holiday in one day to repair his roaster. But beware this is in Taiwan, where the bullet train is available to traverse the whole island in about two hours.
I wonder if a Taiwanese customer is to write Ambex, Probat or Diedrich in Chinese, and will receive a response in Chinese....