No direct experience with the Ahwahnee but I have the Pinon (very similar to the new Hilleberg Allak) , basically an Ahwahnee with an extra pole and two vestibules, and the Lighthouse.
All of them use the Bibler design but since BD took over they have released some of the designs under the Black Diamond label using lighter weight Epic rather than "Todd-ex" .
I never used the two side by side (....) but it is my opinion that the Ahwahnee would be warmer and it is more rain proof (never had any drops inside the Pinon) , Epic will wet out after several hours of heavy rain ( with me anything from 4-5 to 7-8 depending on the volume and size/speed of the drops) . When fully closed the Lighthouse will let more light in .
Keep in mind that there is only one door on the Lighthouse, the new Ahwahnee has two.
Franco