I've never used that brand, but of the several I've used the Whisper's are my favorite for the lower noise levels.
The numbers you stated are:
2.3 Watts is the amount of power the unit consumes (this is what effects your electric bill)
1.4 lpm is liters per minute, this annotates how much air the unit pushes for reference.
Once you attach 10 feet of airline, etc, the lpm is reduced, but these numbers are just to give you a point of reference between different units.
What size is your tank?
In the DC Metro Area? Check out GWAPA