I am relatively new to the 100 and did sell a Hemi powered Grand Cherokee for the 100. It certainly doesn't have the 'spunk' the Grand did, but the power band feels unbelievably smooth and consistent. The 100 also has 180k more miles on it. As with any vehicle it could use more power, but more power is totally unnecessary to serve its intended purpose.
My 99 is basically stock and I feel it does great, here in Kansas and when I took it to Colorado. A 5th gear would be nice on the interstate to drop the cruising RPM down. I look forward to seeing how the 100 performs off the pavement in the High Country of CO in a few weeks.