Can bricking my GT - I9100 damage my antennas?
You shouldn't be able to damage your hardware through software.  It's obviously not impossible, there are things that control voltages and so on, but in general it's not even worth considering.

The Note and the SGS II have different hardware and software; there's no reason to believe that the difference in bars you see is anything other than normal.  If your connection has a problem, you'll notice when you try to use it.  Don't rely on the bars.