I think sometimes people place too much of a premium on batch size. The large commercial roasters are awesome, but there are quite a few trade offs for the luxury of running fewer batches. I don't mind spending time roasting, and would rather save time on the cleanup and setup parts.
Larger roasters take much longer to heat up, and it is hard on them to do just one or two batches and then cool back down. On my tiny Quest, I run 3-6lbs a week mostly roasting every 3 days or so, a dozen batches at a time. It suits me much better to have a dozen different small fresh roasts than a single roasted kilo. The drums like multiple batches, the Quest takes a pre-warmup and two or three batches to really come up to temp.
The convenience of roasting on a large roaster can take a hit when you consider how much different your roasting environment will likely be. A small electric home roaster can be used relatively safely indoors, with some makeshift venting. Plug it in, and go. Put it away when it cools off.
A commercial roaster installation using natural gas is quite the experience, often requiring pressure adjustments on your home service, double wall permanent ducting, etc. Propane tanks over 1lb cannot be legally stored or used inside a residence, and depending upon where you live propane isn't quite as accessible outside when it gets damn cold. Installing a commercial roaster inside your house is also going to be problematic for your homeowners insurance. (if you hold a mortgage, your bank isn't going to be up for this) Keeping it quiet could expose you to a large amount of financial risk.
The smoke and fire safety issues are batch size exponential. In my neighborhood, I would likely have to run an afterburner if I went too much over a pound. Roasting big batches doesn't encourage experimentation, pooching a roast with a new profile is bummer times batch size. If you ever wanted to roast a coffee three different ways to see which one was better, tiny batches rock. Roasting smaller than rated batches can be tricky on the big drums.
If anyone is still reading, I will wrap this up by saying that you might want to look at a commercial roaster like a 240v 3 group commercial espresso machine. Sure, it is worth the hassle and counter space if you are going to leave it on 24x7, and might need to pull 30-50 shots an hour from it. For home use most people would find the machine less convenient and more costly per shot than a nice prosumer unit. And you can use the extra money you saved on a better grinder!
