Yes I found that my insulin use dropped..
On injections I used 16 units of background insulin, but with the pump dependant on what profile I using, I used between 7.6 and 10.4 units of background..
And I've also found savings in bolus, because now I inject what I need, and not stuck to injecting a whole unit when I need part of a unit..
Different people will experience different levels, as it will depend on various factors, but it's the fine tuning of the background insulin with the pump, that probably saves the most.