A bond is only as safe as those who have issued it. Not my cup of tea as:
1. Owning your own metals is more "private" as only you know what you have unlike a bond with a paper trail
2. What's the financial position of the bond issuer? Will I wake up one day to find the vault cleaned out, my metals gone and all I have left is a nice framed piece of paper (certificate)?
3. Whats to stop the bond issuer using my metals in other investments and then those creditors being higher up the food chain in the event of bankruptcy thereby getting certificate holders metals?
From Opes Prime, Bernie Madoff, Henry Kaye and a myriad of others, many have lost a lot because the people running the proposal seemed like good guys but they turned out to be anything but.
*NOTE* I dont know the people/companies behind this particular investment vehicle and my comments are just made generally.