I used to have a '64 Super Reverb and experienced a hell of a lot of feedback above 4, and the same noise, using any of the distortions on the Zoom.
Unfortunately I had to give it back to it's rightful owner; I just had it on loan for a few months.
(it was in pretty bad condition anyway)
I think that the Danelectro would be a good option considering chorus and delay are the only main features that I would be missing on the Zoom, and that I would get much greater customization capabilities through it.
Your help has been much appreciated, I think I will definitely go for a Danelectro Chorus/Delay or something similar, thanks.