Developing transport units is not something I see many players do. With the exception of the speed of which the unit travels on water, the attacking and defensive strength doesn't really increase much, and it's simply not worth it. What WOULD be a big motivator for developing transports, is a reduced boarding/increased disembarking time .... now that would make it worth developing these units.
so ....
1) Speed of Travel - the increases currently are good - I see no reason to change this progression as research occurs - seems good
2) The increased combat defensive capability - not enough of a change to be a factor and motivate anyone to develop this unit
ADD ....
3) Improved Embarking (Boarding) times and Disembarking (landing) times as development and progression occurs.
***There should always be a reasonably long time lag when disembarking, but maybe it goes from 5 hours, down to 1.5 hours through 4-5 levels of unit research.
so ....
1) Speed of Travel - the increases currently are good - I see no reason to change this progression as research occurs - seems good
2) The increased combat defensive capability - not enough of a change to be a factor and motivate anyone to develop this unit
ADD ....
3) Improved Embarking (Boarding) times and Disembarking (landing) times as development and progression occurs.
***There should always be a reasonably long time lag when disembarking, but maybe it goes from 5 hours, down to 1.5 hours through 4-5 levels of unit research.