If you don't mind a steep learning curve, and are willing to use it as a manual roaster with somewhat uneven results, you will experience drum-like quality coffee roasting.
Positive Product Points
Drum-like quality roasting from a home roaster. Can roast in all temperatures without modification. Roasts up to one-half pound.
Negative Product Points
Meaningless roast numbers. Poor chaff collection. Widely fluctuating roasting times due to ambient temperature, at least in older models. Difficult to hear cracks. Peaberry and other small beans can't roast in this. Lots of smoke produced. Can't visually monitor the progress of the roast. Roasts somewhat unevenly.
I know it's hard to imagine not wanting to buy a product you have used almost exclusively for coffee roasting over the past three years, but that's only because I have learned to work around the many flaws of this machine.
For the ADVANCED roaster, the Alpenrost produces drum-like quality in a home roaster. Because the drum is a perforated steel container, small beans will get caught in the holes and burn because they're not moving inside the tumbler. Chaff is supposed to be collected in a dish underneath the roasting drum. Although much of the chaff ends up there, a good bit is left inside the drum or through the fan to the steam screen.
I bought this from a private owner, but it was in good shape. To its credit, the machine can work in any outdoor temperature I've tried it in, including below freezing. Most air roasters would need to be placed in a cardboard box to preserve the warmed air around it.
You'll need to use this machine outside because of the smoke produced, especially when it goes into its cooling mode. I imagine a great deal of smoke is held within the machine until it blows it out at this point in the roast. I haven't noticed it adversely affecting the flavor of the roast, however.
As the beans tumble in the slanted shelves built into the interior of the drum, the sound is muffled by the dark multi-layered cover. This reduces your ability to discern the cracks, which is an absolute must. The 1 - 15 roasting numbers are meaningless because of wide fluctuations due to the ambient temperature, the type of beans, and the amount of beans being roasted.
The outside of the lid is dark plastic, but inside it is lined with shiny stainless (wanna bet?) steel to reflect the heat back in to the drum. Yes, this steel stains quite easily and is the most important part of the roaster to keep clean. That doesn't mean you can ignore the doors to the cooling fan that also need a good wipe with a damp sponge after every roast. The steel interior emphasizes the need to keep the lid shut throughout the roast. The design doesn't allow for the roaster to see the beans as they progress throughout the roast. You must rely on experience and a keen ear for cracks. This is NOT a newbie roaster.
Single origins do better than blends because of the somewhat varied roast. This isn't to say that you'll get French and City in the same roast, but I generally cull out more than a few beans everytime whether it's a blend or not. This isn't necessarily a bad thing, especially if you're roasting for espresso where a little variation can add a pleasant complexity.
Speaking of espresso roasting, it is notable that the flavor of these beans compared to an air roaster like my FreshRoast+ is readily apparent. This does a better job of mellowing out the beans, particularly in an espresso's generally darker roast. That's why I've learned to overcome the Alpenrost's drawbacks and continue to use it successfully, but if I had to do it over again I would have gone to the Galloping Gourmet / Stir Crazy combo I have been using lately.