I 'skim' nzbmatrix probably 3-4 times a day, about 25% (or 1 out of those 4) it will be down. Or I should say, because I don't try and ping it, perhaps the route to it is broke.
But, 25% is pretty bad. Don't know if they are working on it, or, from looking at the tracert to it right now, looks like it's either moved (slightly) or some routers close to it have had their routing changed around. But it's still in Toronto (or thereabouts).