I believe this will deter exactly zero bandits.
In response to a violent robbery that left five people dead (according to EnglishRussia), The Private Bank of Russia attached these stickers to the sides of their cash collecting vans showing what’s "really going on inside" (sure sure).
Hey, real, experienced mercenaries are expensive.
I think stickers that read "NO RADIO/CASH" would be a more effective deterrent.
Either that, or maybe spring for some armored cars.