Heh. Here's a bit of interesting perspective. We downsized from a 15 passenger Chevy Express 3500 to an Atlas (family members graduated and moved out). The Atlas is wonderful by comparison: nimble, tunable, better mileage, better seats, sound, amenities. The only thing it doesn't beat is the cargo and towing capacity, and the increased HP and torque of the 6.0L engine.
I don't think my driving style is particularly passive. I consider myself an aggressive-defensive driver (be in front of the bozos if you can; don't be the fastest driver on the road, but don't be the slowest either). That said, I've not really noticed a lot different between Normal, ECO, and Sport modes. Yes, I can tell the shift points are different with Sport, but the local driving conditions aren't really conducive to that making a difference, I guess. Flooring it to accelerate to 75mph up an incline to merge onto the interstate seems to take about the same amount of time in all 3 modes. I'm pretty satisfied with the performance, though I would not be opposed to re-chipping it after it's out of factory warranty and into extended warranty territory (should such a chip emerge—I haven't heard of any yet for the 3.6L in the Atlas, though there were some for older models).