Here's another example of another iPhone developer is doing with their iPad plans:
http://www.geardiary.com/2010/03/15/...t-on-the-ipad/
The makers of Pocket Informant are not concerned about having the first or second app out the door in the productivity world. The article mentions that they will try to resize the current Pocket Informant app for the iPhone working on the iPad. Then they'll take their time and work out a brand new version of Pocket Informant for the iPad.
This is the same strategy that OmniGroup is taking. Agree with it or not. I think it's better to make sure OmniFocus for iPad is not a rushed product.