General Roasting Profiles?

After roasting with poppers for about 4 years, I finally broke down and
bought an I-Roast 2. I realize that I-Roasts are not calibrated so
each one roasts differently, but I am wondering if there are any "rules
of thumb" which can be applied to roast profiles. For example, I'm
guessing that a good profile for Columbian will not work as well for
Sumatrian, and I might not want to use the same profile for Sumatrian
for Puerto Rician.

The roast profile I'm using now for everything seems to be the
standard: 340-2, 400-3, 450-6, stopping it in stage three when it
looks good.

Sumatrian, Islands, and Central Americans are the three main groups of
coffees I drink. Anyone have any suggestions on how the general shape
of the roast profile might differ for these general types of coffees?

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