That S1 5.9 is off the scale goodness! I'm now on my second ('08 and '09) and absolutely love them. The window I've never had any problems with, and to be honest I've given mine some good hidings. The Blade is a gutsy sail with more bottom end, so if your mainly onshore cross-on you may want to consider that, but you won't regret the S1...
If you get it, let us know how you get on!