We tried to climb Cayambe on March 4 and 5, it is very icy, crevasses are open, there is barely any snow, we did it until "picos jarrin" (5000 m). Conditions change rapidly. On november/2005 it was covered by compacted snow, so the climbing was easier, we did it in 5 hours.
As of November 2013, the refuge is being renovated. One of the kitchens had been torn out and the place was taken over by the workers. Not sure if climbers can sleep there until the renos are finished. Best to check ahead.