Finished my first few roasts with my new used Sono today. I am very happy with this machine! I did 5# of El Salvador greens - 1/2 at setting 5 and 1/2 at setting 6. Results look great, very consistent in color. I don't see a big difference between those done on 5 and those done on 6. Is this about right? One notch up or down brings only a subtle difference in the result. I would call the 5 Full City and the 6 not quite Full City +.
I was able to hear 1st crack on all four roasts, but only heard 2nd on one of the 6's less than 10 seconds before the end (it may not have happened at all on setting 5 I'm thinking).
I won't get to taste the results from this group. These 5#'s are going to a U.S. Army unit from Fort Drum serving in Afghanistan. All indications are that the coffee would be real gooood 
Bob,
My understanding is that voltage at your location can play a role in the setting you need to set to get the results you want, and the Temp sensor comes into play. If the sensor is older, slightly dirty, etc., then it will also effect the setting needed. I will admit I prefer lighter roasts on most greens. Sometimes I do go to #5 on a Sumatra, espresso roast, etc., but generally I'm at #4.....
BTW, THANK YOU for roasting for the troops!!!!!!!!!!!!! 40# went to the combat zone to 8 different units 10 days ago. I just got confirmation that one has gotten there! Coffee for Christmas!!!! jim