Not to beat this subject to death, but it is curious that
brass-on-aluminium is used now and then in mil equipment as in
this BC-610 var cap now on eBay, item No. 185140328932. Note
brass spacers between Al capacitor plates. Mike, W6MAB
It's an interesting subject, Mike. If those spacers are tin plated,
then it would be less of a potential problem. But I think Roy
Morgan's earlier observation about the environment was the most
accurate assessment - if it ain't wickedly wet or continuously high
humidity, then it won't be much to worry about. If your environment
looks like that for the set below, then okay - probably needs
another design.