No its not the data connection.

You have so many processes running in the background (some for Android, some for Google, some for Samsung, some for your Syncs, some for Apps)... and they all add up.

The problem is, after your device Sleeps, most of these prosses must stop running. Not immediately, but after 2-3 mins they will. And only a handful should be working (radio status) or only working in bursts of intervals (for instance for 2mins running for every 30mins).

This is called "Deep Sleep", self-explanatory. The reason the iPhone has better battery life than ANY single android phone (with similar battery/modules) is because Apple controls the software entirely. They've "perfected" the efficiency of the software towards the user.

This is not the case with Android when each tasks is fighting against one-another in any state; which leads to prolonged use of the ram, processor, radios... pretty much the entire SoC. Ie, android is inferior to iOS because it is less effecient... and half the fault is by the OEMs.

Gingerbread-NOTE has a good effeciency/working Deep Sleep. Most of the ics kernels/roms (inc. Samsung Official) have difficulty entering Deep Sleep. So you end up using alot of battery without doing anything.

I used to go from 90% to 85% with phone "Sleep" for about 6 hours in Gingerbread. After "upgrading" I would lose the equal amount in about 20 minutes. Now I'm using Thorv15 and AOKPb40 (and its mostly patched up)... I lose it in about 1.5 hours. So its still not as good as Gingerbread but much better than the buggy ICS ROMs... and Frankly I think it will improve a little more as it matures further maybe even to the 3 hour mark I'm hoping to reach.

Though remember, not every NOTE is created equal... and what you put in it, and how you use it will create mountains of differences.