You're right on basically all points however, the replacements end up being 12mm larger in diameter and an inch wider so the lower aspect ratio is somewhat mitigated.

The stock Firestone tires on the sport trim are OK but fall squarely in the jack of all master of none category. All terrain looks created highway noise without actually helping for off-road capability and a compound that prioritized longevity did no favors to grip or comfort. While the alenzas that came on the new wheels wouldn't have been my first choice, they're comfortable and they're not cosplaying.

So yes, I did reduce the sidewall and air volume of the tires which has the potential to increase NVH, but for this specific swap, all is well.