I think the proportion of home roasters who really know how to roast and have the equipment, real estate and patience to do it right is quite small. What I see over and over again are people whose only reference points have been mummified supermarket beans, then buy a little air roaster, enjoy their first fresh beans and conclude that their four-minute roasts are the pinnacle of the roasters' art. I will never forget the SCAA Homecoming a couple of years ago, where a new home roaster from San Diego with a Fresh Roast flew into a tizzy, because Marty Curtis dared suggest professionals with commercial equipment might do a better job of roasting.
I think this is less true today than it was a while back. In the 1990s and early 2000s, there was a good deal of arrogance on alt.coffee when it came to both espresso and home roasting. Both have diminished considerably since the fanatic amateurs and dedicated pros have found each other. When I started out, around 2000, we amateurs simply didn't know about this group of pros, and we were fairly secure in our arrogance.
Obviously, a pro who's just as committed to quality will do better than an amateur. However, I'm not about to stop homeroasting. I'm going to take some flak for this, but I think
committed amateurs keep the pros honest. We aren't enough to be a large market segment; but we are the largest segment of coffee talk, to which both pros and the wider buying public for quality coffee, who will browse the net for info, listen. I enjoy cooking and roasting coffee; one of the things I enjoy most is getting a dish or a shot where I'm scratching my head in admiration asking "how'd they do that." If our talk and arrogance disappeared from the net, one of the goads that is increasing quality would disappear too.
However, given the total volume of Professionally roasted beans out there, I'd also wager the ratio of quality home roast to poor home roast may be about the same as quality Professional roast to poor Professional roast.
There is a distinction between roasting and selecting coffees. One area where artisan specialty coffee roasters are dangerously arrogant is in their assumption that their roasts are technically better than the suppliers of mass market coffee. For mass roasters, it makes sense to pay megabucks in roasting technology and research if it allows them to get the same cup quality with coffees that cost a few pennies less per pound green. For instance, the last time I roasted Vietnamese Robusta, I got a cup that tasted like the water from a hot dog vendor's cart; the mass roasters get something from the same beans that tastes forgettably like generic coffee. This is quite an achievement of the roasting art.
It makes sense to assume all this investment creates better roasters than the standard shop drum; and it's important for us to keep an eye out on where this technology is going. I sometimes wonder how good COE coffee could taste if roasted on the gear that can put a semi-acceptable face on Vietnamese Robusta.