If you do go with the "hardwood floor with a carpet" look, see if it'll work to put the carpet at the place on the floor where you're liable to get a direct "reflection" of the sound. If you have a hard time locating that area for each speaker, sit in the "primo" position and have someone move a mirror along the floor till you see a reflection of the speaker.
This primary, direct reflection is likely to be the most notable one if the hardwood DOES cause a problem. I have the same issue here with hardwood floors throughout the whole house and will replace my current living room rug with one just a tad bigger to cover that point!
