The larger home coffee roasting machines like the the Behmor, HotTop or Gene Cafe are drum (i.e. conduction) machines and give a slower roast along the lines of the manual methods and commercial drum roasts. Roast times will be more in the range of 14 to 20 minutes. Each of these machines allows great control over the time, temperature and roasting profile than the air roasters; generally the more expensive the machine, the more control.  The comparison chart linked below has updated notes on size, cost, pros and cons.

The batch size of these roasters is generally from about 8 ounces roasted coffee (HotTop and Gene Cafe) to up to about 10 or 12 ounces roasted coffee  in a Behmor. Eight ounces of green coffee gives you about 11  scoops of ground coffee - that is just over 52 ounces to 84  ounces brewed coffee depending on how strong you like your coffee.

Drum roasts tend to develop the body of a coffee, and can mute the brightness. Some brewing method, like espresso, tend to favor coffees with more body instead of brightness, but there are really no hard and fast rules when it comes to coffee roasting.  If you know you love coffees with crystal clear brightness, and moreover need only a little coffee (1 to 2 coffee drinker household) you might think about an air roaster instead. 

Drum roasters are also effected by line voltage and ambient temperature, but to a lesser degree than the air roasters. These machines also tend to be more durable in our experience as they do not require the high fan speeds that the small air roasters do, so they last longer.

Here are some helpful links:

• Home Roasting Basics,
• Choosing a Home Roaster
• Visual Guide to the Roast Process.
• Home Roaster Comparison Chart