When you move up a size in the width you kind of "squeeze" the tire up from the rim since it isn't also getting wider. Sometimes you can compensate by dropping the sidewall percentage to a 60, but then the tread will "creep" down further and you'll still have an odd profile. Better, but not ideal.
Will you notice? Who knows, what you will notice is new rubber. I went from dry-rotted tires with the front in entirely the wrong size (110/80/17) to primo rubber in the correct size and the change was dramatic. Would it have made a difference if I had upsized? Yes, I would have still had fresher rubber than the crap that was on there initially. Would it have mattered to me? Probably not since this was my first "fresh" set on the bike.
Tires are kind of a consumable good, it's not like they'll last forever and you're stuck with them. If you can score a screaming deal on them locally, give it a shot. In worst case scenario, you'll have to get a new set eventually anyway. YRMV, and since it's winter, why not just save the money since I doubt you'll be riding in Dec. in Kansas anyway.
-Randy