Much depends upon the specific DME you are using. I've found vast differences between the contribution of Briess Light DME and Munton's Light DME. I usually plan on around 90 grams of DME filled to 1 liter with water and boiled for 5 minutes to give me a gravity reading of around 1.038 to 1.040.
In terms of your equipment profiles giving you different numbers, you need to look at the deadspace and losses associated with each profile to determine the differences.
Lastly, I second Tom's recommendation of building no less than a 1 liter starter. The growth rate with lower starter sizes just does not seem to match the models that are available. In terms of any potential over pitching concern, there is a wide range of cell counts which will give you the same end results and you need to be 3x or 4x the recommended cell counts to get there, IMHO.