Surprisingly enough, Grey Dawn seems to be one of the better floribundas in my garden, healthy, bushy and blooms well; she also recovered from freezing to the ground in the winter of 2011/2012 quickly.
Sure, own root is not the best solution with some of the roses, but then again, plenty of the "blue" roses do not do all that great when grafted either, otherwise we would see Azubis in every garden (as it is sold practically by every generic garden store and I have yet to see it growing in any garden). x)