The Behmor 1600 is a high-quality, push-button appliance that will roast up to a full pound of green coffee beans. It can be as simple as putting the green beans in the basket, inserting the basket in the "rotisserie" brackets, and pressing two or three buttons. If only the coffee itself were always so user friendly.
The Behmor has five "Profiles", that have a fixed heat application curve over times; these range from aggressive, full-on (P1) to more gentle, slower heat (P5). It also has four "Programs" A-D, but these are largely just time differences. There is a setting for bean weight for of 1/4, 1/2, or a full pound. You can also adjust the time manually within a limited range depending on the profile. All of these are selected via membrane buttons, and the results are shown on a microwave oven-like digital display.
However, the design of the Behmor is in general to take the coffee no farther than the beginning of second crack. Depending on how good your wall voltage is (I use a variac to keep mine up) and how well you have maintained your machine (more below), you might not even reach that far. But it was designed as a high-safety appliance, in view of the fact that you are putting a potential fire source on your counter. It is indeed possible to roast darker than second crack or to have some finer control over the roast, like by roasting less than you tell the machine you are or by adding time to the default, but these by definition void your warranty if you go deep into second crack. Sweet Maria's has a good tip sheet on how to get better or darker and more flexible roasts out of the machine, so I will let you search there to find out more. But it is impossible to create your own temperature profile or to go outside of the bounds of the pre-programmed settings of time and heat application.
The machine uses a wire mesh cylindrical basket, with a spring-loaded catch tray underneath. Two infrared quartz heating elements span the back of the chamber, and are blocked by a wire grid so that you can't easily get to them. As the machine roasts, the basket spins while paddles within the basket stir the beans. Any chaff falls down to the tray. The wire mesh basket has fairly small spacing, but even so broken or abnormally small beans will fall through this, or get caught in the mesh or between the wires. The machine also has a smoke suppressor on the exhaust, so less smoke is produced; this will reduce your chance of setting off a smoke detector, but won't eliminate it. Especially if you roast toward second crack. I ventilate with a fan facing outward in a window, and close the door so the smoke detector is on the other side of it.
Ideally the tray would catch all the chaff, except that it doesn't really. It gets all around the inside of the chamber and it's easy enough to vacuum out. A strong vacuum with a crevice tool is one of the best friends to have when roasting coffee anyway. Chaff does tend to get through the crevices of the box into the inside of the machine, and this requires some maintenance to clean out (more below). The basket, the tray, and the sides of the chamber do tend to become darkened with smoke; the manufacturer recommends the use of Simple Green to clean these. I've also found that an aggressive double-detergent wash in the dishwasher does an even better job than I can with my hands on the basket and chaff tray.
The Behmor comes with some well-written and clear documentation; several updates and addenda have been published on the Behmor website (http://www.behmor.com/). Be sure to read these as they have some handy tips, for both regular maintenance and also how to periodically clean out the inside of the machine-- not the part where the coffee roasts, but the part inside the outer cover. This is necessary because the unit contains a couple of fans; one that pulls air from the right side and one that pulls the inside air out through the exhaust. Because these are small computer-type fans, they can get gunked up after a short time. (Chaff also somehow magically gets into this area... maybe via quantum tunnelling.) My roast times were getting longer for no apparent reason, until I did some research and read the maintenance docs. I opened mine and cleaned the dust that had stuck to the fan blades and clogged the airflow, and my roast times shortened again.
Behind the quartz elements is a reflector; I am a bit concerned that as this darkens with smoke, it will reflect the heat less well. It is impossible to get to it to clean it without cutting out the protective wire grid or taking the unit apart. I can already see that it has a brown sheen on it; I've roasted maybe 25lbs or so through the unit. We'll see if this becomes a problem.
In general I roast 10oz of green beans on a P3 curve with a 1lb setting and a max time limit of 23.5 minutes. I could roast more than this, but I find that it is about what I will use in a week as the sole consumer. I stop the roast near the beginning of second crack, with about 5 minutes of time left on the clock. I am not a fan of bright or acidic coffees despite what subtle flavors can be found in light roasts, so I tend to roast darker and use heavier coffees like Indonesians and Sumatrans, or aged/monsooned coffees. I would rather have plenty of time on the clock and stop the roast when I want, rather than be met with a deadline zero before the roast is done.
Of course this type of roast will produce more smoke, even if there is a smoke suppressor so be prepared to vent the room and keep smoke detectors isolated from it. The Behmor is not really directly ventable; if there were one enhancement I would like, it would be for it to have an exhaust that was easy to attach to a vent hose of some kind. Instead there is a flat vent plate covering the exhaust, that disperses the heat more gently and keeps the external temps down.