Well, the bridge and tailpiece don't fall off when restringing. That's about it for performance No tonal improvements that my ears can pick up but it may make a difference to someone, somewhere in that respect.
Look for Marquis Distribution on the web, they're in CA. Tell them that you have a Heritage 535 and they'll fix you up with a chrome/nickel/gold/black/aged set in a couple of days. No drilling or other messing about, just a straight swap As you say, they look great, and that's the main reason for me putting them on.