-December quarter beats estimates
-But how much upside?
-Solid earnings should continue
-Stock should withstand competition

By Eva Brocklehurst

Sleep disorder product specialist ResMed ((RMD)) has received a warm reception from brokers as it delivered a strong December quarter. However, there are some doubts as to how much further upside can be expected as the stock has bettered forecasts substantially.

Margin was again the driver, at 61.8% in the second quarter it was 90 basis points higher than Macquarie had expected. Product mix and supply chain efficiencies contributed to