It's not just 6 vs 8. Sno mentioned the TrailBlazer. The straight 6 in the TrailBlazer had such a flat torque curve, and IIRC produced 90% of its 275 lbs/ft by 1900 rpms, it was a perfect tow vehicle. I had 2 of them and never wanted for more power. The V6 in my Blazer was a pig.
My first impressions with the Jeep is that it is less responsive than the MDX. This might change with a few more miles on it. But, once it responds it's like a rocket. I still think if they left the 3.45 rear with the Hemi, it would be a killer.
I have fulfilled a childhood wish of owning a Hemi ... so all is good.