An interesting topic that can stir many long-winded and highly opinionated discussions beween participants holding diverse opinions - especially at a venue such as the roasters guild. I once heard a roaster state that "drum roasters suck", while another responded cheerily that "fluid bed roasters blow".
I have done extensive comparative cupping and have roasted coffee with several different machines of different brands and styles. While I have some well-formed opinions and preferences of my own, the only useful disclaimer to the following statements is to: avoid seriously flawed equipment.
Nearly any roaster can roast coffee. Many can roast coffee quite well. FRESHNESS, QUALITY OF RAW MATERIALS (green), & THE SKILL OF THE OPERATOR mean much more in the equation than the particulars of the equipment.
Furthermore, a coffee can not become better then the intrinsic character of the green. A skilled roaster can reveal more of the cup characteristics and can tailor the roast for different brewing styles. However a poorly skilled roaster can easily dull the coffee during roasting or blend and roast a coffee poorly suited to the brewing style (particularly when brewing espresso). Similarly the coffee can yield a cup far below the potential intrinsic character - if the coffee is poorly blended, poorly roasted, poorly packaged, poorly stored, not fresh, not ground/brewed fresh, brewed poorly, or served poorly.
Concern yourself less with the specific details of your roaster's equipment and more with their cup quality, commitment to freshness, and commitment to service.
It's funny how some people can have such strong opinions about one or the other and have never tried the opposite.
I used to think air roast coffee was crap, until I tried some in Seattle at Coffeefest. The coffee was roasted right in front of me and I got to tell you it was pretty good. It was full flavored, nutty with a mild acidity and very smooth finish. I was impressed. It was a dark roast, not Starbucks dark, but darker than full city, but it didn't have that burnt aftertaste you sometimes get.
Drums have and do make great coffees, but I think it's foolish to discount the advancemnts being made with fluid air technology.
But that's my opinion nd I want to hear more of yours.
Some coffees take well to it some don't
If you roast too fast, then again it can be a problem with certain coffees
Water quenching isn't a good thing on the very large FB systems
It's cleaner than drum roasting (smoke wise)
Operator require a little less skill on FB than drum
Not all drum roasters work the same way (gas, electric and also the heating methods, conduction, convection and radiation)
There is FB and Hybrid type roasters
A lot depends on the coffees you wish to roast, the batch sizes, skill of the operator and any smoke/problems or issues....there isn't a clear answer.
I have found many drum roaster sites but who sales the fluid bed systems? The only one I have been able to find so far is Sivetz. Looking to see what is available for shop use with a capacity of 5kilo's or so.
I have used both on a commercial level, as well as home roasting versions. The a drum roaster will produce better(read...more complex) coffee, than a fluid bed air roaster. But this topic always comes up, and causes problems, and each have there own place in the industry.