Never ridden a Cordoba or a Feather. However I would think a relatively inexpensive aluminum bike would ride harsher than a relatively inexpensive steel bike, all other things being equal.

My sense is that people choose aluminum more for the look than the ride, so that point may be moot. If you like the fat tube look get a Cordoba, if you like the classic track look, get a Feather. Higher end tubing of either variety offer better compromises between stiffness and comfort so there is probably less difference due to the inherent properties of the material than there is at the lower to mid range.