I just rode the Gran Fondo Ephrata on 28s. A Pasela tourguard up front and a Conti gatorskin in the back. Worked great. About 30 of the 80 miles of this ride was gravel. Definitely driveable gravel, except for one gnarly section, could have had a mountain bike for that section, but it was only a couple miles, so doesn't make sense to make gear choices on such a small percentage of the route. Of course for the 50 miles of paved road you appreciated the 28s.