I have the SC plus a 5-speed - the two combined make for a very driveable vehicle.

The two biggest places I appreciate the supercharger - when I go to dive into the carpool lane on the freeway (getting ready to do that in about 5 minutes) - the extra boost gets me across three lanes of traffic with no fuss and when I was on the roadtrip to Smyrna for the plant tour - I didn't have to downshift maintain speed, even on some pretty good hills. Some of that is the 5-speed, some of that is the added power the supercharger gives you. My cruise control maintained constant speed with no problems. Makes my highway driving that much more enjoyable. I rarely downshift to pass on the freeway too - to me that's a major "quality of life" enhancement that more than justifies the SC. Extra power always on demand - you can never have too much power

So, while it may not be a "snap your neck" performance increase (the X is a truck after all), I find it does make the X a much more driveable vehicle overall. It's not just one or two improvements, in my opinion my overall ride has improved. And yes, I have driven normally aspirated (i.e. non-supercharged) Xterras for extended periods of time as rentals - i.e. weeks at a time, not just dealer test drives - I took over a year to decide which Xterra to buy and for me it paid off. I have absolutely no regrets because I knew EXACTLY what I was getting I wouldn't do it any other way!

Oh, and as others have said, the premium fuel is no big issue. For me, Costco has premium fuel for 10-12 cents difference from regular. Even if it was 20 cents like some have mentioned above, big deal - I bought an Xterra instead of a typical $35-$45K SUV, so I'm still ahead even with paying for the premium fuel