Challenge tires are a gamble, I know people who've had no problems, but when I visit the 30 or so bike shops per week I see the writing on the wall, mostly in the form of delaminating tread from it's casing. All models from Challenge, including the tubulars which have another problem, most are sewn crooked.
If you can fit 27 wide you can probably do 28mm which is a more common size.
I've been using Continental tires for many years, and relied on mostly for my daily fast training, high mileage, touring, commuting, and racing, everything I guess.
This year I'm going to start testing more models from Clement, been using their CX tires for the last couple years and they've been great. Interested to see how their Strada LLG clincher is, comes in 28 too..