I have the Gaia II's on my Spatial M'3 Sapphires on a hard wood floor.
They are very open and dynamic sounding especially in the bass and lower midrange. They were a huge improvement to just spikes or the rubber feet. On carpeted floors I would imagine spikes would be the way to go as they connect with the hardwood floor underneath your carpeting. My Vandersteen's were spiked to the carpeting and also were greatly improved in the bass and dynamics as well.
They are very open and dynamic sounding especially in the bass and lower midrange. They were a huge improvement to just spikes or the rubber feet. On carpeted floors I would imagine spikes would be the way to go as they connect with the hardwood floor underneath your carpeting. My Vandersteen's were spiked to the carpeting and also were greatly improved in the bass and dynamics as well.