I'm going to take their recommendations with a grain of salt because all of their experience is in South Africa and Arizona, where shade is usually bright shade. I have that same type of climate here, and although I grow many of my roses in the shade, I wouldn't advise people in colder zones to grow hybrid teas in partial shade. Most hybrid musks and some other roses will do well in partial shade in any location, but other roses typically will produce fewer blooms, and blooms that are smaller than the usual size, under those circumstances.
