Hi. I've had the Edirol R-for about a year now, and love it. - I just bought the H4 2 wks ago and experimenting with it.
As someone said above the H4 has no easy way to change the input level when recording. - Also as a drawback it doesn't have Time of Day stamp for the files, or give any idea on how much space/time is left on the memory card in the display. You CAN call up the filesize of each file, but you would have to add/subtract to figure out approximately how much space you have left. - Still have to try attaching via USB to a computer but other than the above it's not too bad. I think I'll use the Zoom as a backup though because of the lack of the space/time and the timestamp