I was just thinking of the same thing as I'm about a month longer in to mine. I'm at about 21K and have no regrets. It's funny, towing I notice much less of a difference than as a daily driver. My towing experience with the 6.4 is nearly identical to the Duramax I came out of. As a daily driver the 6.4 is definitely a step slower than the Duramax (yes, it was completely stock). That diesel had just crazy "secondary" power. Meaning, it could accelerate off the line okay but when you really laid into it, could just flat out haul. The Hemi has power but just not as much. It's okay.... it's about time I grow up and stop racing everyone from stop lights :)
Overall, the Hemi is a great truck and I'm super happy with my purchase.