Hi maggiesp,
You can read more about the Alexis (or any mattress with thicker latex comfort layers) vs the Bamboo Bliss (or any mattress with thinner latex comfort layers) in post #2 here and post #2 here and post #3 here.
For most people it would make a noticeable difference (6" of latex would be closer to the “feel” and performance of an all latex mattress than a thinner latex comfort layer) and as jefmoody also mentioned the Alexis also has more options to fine tune the feel and performance of the mattress compared to a mattress with only a single latex layer.
Phoenix