I think the worst bit of this route will be the tak-ma-doon, it was in a right state earlier this year, and the approach to the ford was a nightmare. The last few miles before Aberfoyle are also a disgrace, no way you can open up there or it will be punctures and bust spokes for sure.
Hill wise there is the mini-braes before Callander and there are a couple short stiff pulls along Loch Katrine and a big ring ascent up to the Top o' the World after Fintry, otherwise fairly rolling. Too bad they could not find another 5 miles to make it the full century.