Everything I read on this thread about the iRoast is spot on. I have two iRoast2s - one is a spare. And Like Jspain, I have custom programmed 2 default settings - one for "delicate" beans like the JBM that need a longer, lower temp ramp up time, and another program for everything else. Both programs are maxed to 15 minutes on my machine, with the last stage being the longest. I roast by sight, sound and smell and hit cool when I see the roast that I want. I use the iRoast2 for 150 grams or less of green.
My workhorse is a Hot Top, which is good for 300 grams batches and has terrific manual controls. Even with this, I don't rely on programmed roasting. I have custom presets like for the iRoast2, but all my roasts are cooled manually when I see the roast I want with the time settings maxed out for my "profiles.".
Have fun with the iRoast2. It's a nice little machine.