heres a bit more info as i did a hell of a lot of research before my rebuild....
The table below is an example of these 'metal to metal' relationships, including graphite as conductive non-metal.
ANODIC (Least Noble)
Magnesium
Zinc
Aluminium
Carbon steel or cast iron
Copper alloys (brass, bronze )
Lead
STAINLESS STEEL
Nickel alloys (Incoloy 825,Hastelloy B)
Titanium
Graphite
CATHODIC (Most Noble)
The further apart the metals are, in terms of relative potentials, the greater the driving force in a cell. So, for example, stainless steel in contact with copper is less likely to be a risk than when it is in contact with aluminium or galvanised (zinc coated) steel.
so basically stainless may not rust up and seize and you will be able to undo it in years to come the problem is that galvanic corrosion (the white crud as your ally turns to salt) seen on door bottoms etc is even worse than using ordinary carbon steel.
The ally will sacrifice itself even more... whereas BZP is less noble than alloy so the BZP bolt will sacrifice itself rather than the ally panel and as they are so close the sacrifice will be very minimal... bit of copperslip and it'll never be an issue
what would you prefer at the end of the day?? a bzp bolt that may need replacing in 30 years or an ally panel that will be eaten away far faster??
hence the reason steel ships are equipped with sacrificial zinc anodes (which are only any good if always submerged .. wont work on a landy lol)
Cheers Steve