Thanks for clarifying the situation with the ground cable. :-) And thank you very much for all your hard work on the Indivision AGA MK2. It's wonderful to be able to have a DVI output from the Amiga :-).
Regarding EM immunity, do you think running an Amiga without a top shield is ever likely to be a problem (in terms of system stability) in practical situations/environments? Many people seem to run their Amigas without them without any reported issues related to doing so. It seems some Amiga's (e.g. certain A600s) even shipped without the top shield installed to begin with.