The Hall effect potentially applies to materials that are simply poorer Hall effect candidates.
One could imagine that electrons moving in a DC magnetic field experience a perpendicular force, hence experience increased resistance, resulting in higher IR drops.
nbucska,
We use standard electronics both analog and digital around large dc magnets all the time and don't seem to have any problems. We have some problems with mechinically rotating parts such as Vacuum Turbo pumps but they are usally shielded with mu metal to route the field away from the rotating parts.
-elf