^agree
For regular commuting I run Continental Ultra Sport II for 25$ a tire as there wouldn't be any noticeable gain on my under 20km commute other than making my wallet lighter.
If I were to run on a race, then I would consider the GP4000 for sure.
I ride 25mm rear on my road for a softer ride.
Likewise on my hybrid, I run 28mm in the summer and 32mm or 35mm during fall/winter.
Benefit going smaller was slight save on weight, otherwise I can't perceive any difference between 28mm or 32mm.