Quality of the bass is also important. My new speakers don't go as low as previous ones, but have more even and natural sounding bass. It is likely that larger drivers interact less with room. Port might be tuned for the lowest distortion and not the extension. Especially attack and decay sound much more natural.
With monitors I would be afraid of poor quality of the upper bass plus hump on the first multiple of port frequency. You can either use not-ported monitors (like Lipinski's), close port or apply filter, before adding a sub. Take into consideration that you might not need sub if you get decent floorstanders and your room provides amplification at right frequency. Distance between walls in my room is about 15' hence 1150/15/2=38Hz (1150 is speed of sound, 2 is because it has to travel back and forth to add) fortifying lowest bass (lowest bass string E=41.2Hz).
With monitors I would be afraid of poor quality of the upper bass plus hump on the first multiple of port frequency. You can either use not-ported monitors (like Lipinski's), close port or apply filter, before adding a sub. Take into consideration that you might not need sub if you get decent floorstanders and your room provides amplification at right frequency. Distance between walls in my room is about 15' hence 1150/15/2=38Hz (1150 is speed of sound, 2 is because it has to travel back and forth to add) fortifying lowest bass (lowest bass string E=41.2Hz).