In reply to Frazer:
I must admit to asking myself the same question, why, when I first read your thread. That slope is notorious as we know, due to its convex nature, and being so prone to cross-loading. Match that to the forecast, and my gut reaction would be to stay away.
However, when I read your profile, (as we so often do), I then asked myself again why an experienced mountaineer would have done so, and concluded it couldn't have been cut and dried idiocy. Your description of the route matches what I saw last weekend and the one before that, scoured patches and areas of loading, and you felt, (as did the BMG et al) that is was doable.
So what I am concluding personally, in the interest of learning (which I do believe is very valid, so well done for 'fessing, as the kids would say, and giving us the opportunity to do this), is that the areas of instability noted in the SAIS are just that, areas. I for one preferred the 'cherry toms' rather than the lines on SAIS, as they sort of better represented 'areas', and I said so on the feedback section of the site. I just think it focusses the attention better.
I recall the report from Chris Walker's death on the Buachaille, when a 'mattress-sized' avalanche swept him and a client away.
Conclusion, and re-enforced learning - It doesn't have to be a heavily loaded slope, and even with 'islands of safety', we MUST be very careful when we know loading had occurred, even on seemingly small innocuous looking patches.
Yes?
Post edited at 16:20