The thing that the H4n does that the H2 doesn't which made me make the move (I was VERY happy with my H2) is, it is capable of recording off the line-ins AND the mikes simultaneously, either to the same stereo track or to four tracks (two stereo),

For those of us that play with live bands from time to time, there's always the problem of the board mix being too light on the drums and guitar, and the room mikes being TOO heavy on the drums (or guitar, or crowd noise, or whatever). Now you can record BOTH, then mix them together later.

Brilliant!