no sweat, Angus! It's certainly not a high-quality effect, but as with all of these multi-effects units, some of the effects can be really quite good. I do use my zoom all the time, but for my plain distorted sound, I basically have it on bypass (not quite, but not far off), as the sound of the pickups through my amp/cab is just so brutal as it is :)
Good luck finding something!
Like TO said, the best way when recording is to play the harmony yourself on another track, but clearly that's not something you can do live (in some cases)!
Roo