Last Month 8 Sep to 7 Oct my data usage was on Google Chrome: 1.74GB and Opera Mini 14.30MB.
As you can see Google Chrome take alot of data usage where as Opera Mini take less usage.
Data Saving Google Chrome saved 11% Opera Mini saved wooping 84%.
I just want to point out to GG people if you want to save your data usage for the month I guess you can use Opera Mini which will help you save more data then using Google Chrome. Then again Google Chrome is better to use then Opera Mini base on experince I had using both. The reason I say that GC is faster than OM,
One thing to remember, because Opera uses their own servers between you and the internet you will find some sites which require end-to-end encryption (like banking apps) will fail. In addition, Chrome has data compression but I think it has to be enabled in settings.