David,
In my opinion this depends on the length and nature of your commute. I've ridden both extralight and standard variations of Hetres, and also have extralight Compass tires. These have been on bikes that I ride for the sake of riding, and usually log 30-70 miles per ride on, on various terrain. I do notice the difference in comfort and speed between the standard and extralight casings. By contrast, my daily commute is only 2.5 miles on cracked and pothole-riddled streets and I do that on standard Hetres. For me, the extra comfort of the extralight casing is not really justified on such a short commute. On long trips, the advantages of the lighter casing are more appreciated, and if my commute were longer (say, in the 15-25 mile range) I'd consider upgrading to the extralights.
Anton