Yeah it doesn't bother me, my toy with 32's got about the same or a little more mpg. I was more concerned with engine, i check all fluid's today and everything was good. I've read that it varies like you said and it could have something to do with the ratio. Guy here that's going to do my lift said that taller tire would actually give me a little more mpg. I'll do it anyway's not gonna change my decision =)
So going with the Rubicon 3.5" std lift and later on (when i got more cash) will ugprade it to the extreme articulation one).

- Kotrin