Bonds are still relying on your trusting of a government, corporation, or entity to pay back a debt. That is not the case with hard assets.
It absolutely is the case with hard assets. Unless you are doing your own assays, you are counting on someone else (often a government) to guarantee purity.
That said, I think having some in a commodity fund is generally a good idea just so you can have something that doesn't move as much in tune with other financial markets. As far as price movement goes it is probably slighly worse than stocks b/c there is no dividend, but IMHO the uncorrelated nature of price movement is worth something too.
But that can be said for any commodity, not just PM's. To me, the problem with physical ownership of gold/silver is that if you're really serious about protecting yourself in a financial meltdown scenario, gold and silver may not be worth as much as you think. If the financial system melts down, it won't be that easy to sell your gold for something else as it is now. Plus, you wouldn't want word to get around that you have lots of it at home.
Shotgun shells would probably be a better hedge for that sort of thing. Easily saleable in small quantities, plus you may need to use the ammo yourself. If the financial system does not melt down, you're better off with certificates anyway.
All that said, if you just want a few thousand in gold/silver coins to look at, go right ahead. But that isn't enough to be an investment. If you want physical possession of enough PM's to make it worthwhile, you'll need those shotgun shells and an alarm system, preferably a bull mastiff.