Regarding IT certificated products:

S series
Warranty: 3 years
Operating Temperature: 100% load at 0°C~+40°C and 0°C~+50°C (can be launched at -20°C)

I series
Warranty: 3 years
Operating Temperature: 100% load at -20°C~+40°C and -20°C~+50°C

E series
Warranty: 1 year
Operating Temperature: 100% load at 0°C~+40°C

Please take the lifetime of products and the operating environment when you're thinking about which one of the series is the one you need.