I understand the urge to be a "completist," since I have been one as regards music. (i.e., must own every conceivable regular, live, bootleg, and import record by whatever band.) So logically to be a fully successful Leica completist, you'd need the various Luftwaffe Leicas. So I certainly don't assume that anyone who owns one is a neo-Nazi. But I'd second Matt's vote, that I'd have a hard time (myself, having half Jewish background) owning a Nazi anything, even if historically significant, valuable, taken as souvenir by an Allied soldier, etc. Quite apart from that, I'd worry about being assaulted if I walked about with such a thing (real or fake) showing such insignia.
Thus it was with great surprise that I saw in the latest KEH print catalog just such an item with the insignia on the lens cap. (Fake if I recall correctly, but still I'd expect a reputable shop not to carry Nazi memorabilia.) Isn't this stuff in fact illegal in some countries? (Here in USA where "free speech" trumps sound policy, of course it isn't.)
--Dave