The silver in PSLV is aduited regularly. There are questions about the silver in SLV, and how it moves around. Is it all there? Is it used as colateral for bullion bank shorts? Could there be a problem with SLV one day? Much more likely that a problem with PSLV.
Look at it this way; PSLV can be redeemed for the real thing and has some tax advantages over SLV. Also, SLV's custodian is JP Morgan whom many believe are one of the big powers behind silver price manipulation. Doesn't it seem like a tiny bit of conflict of interest that the custodian of a silver trading vehicle could also hold a massive short position in that same asset?
Here is the first page of the SLV prospectus. It is also interesting to note the following statement on the prospectus that says "The agreement between the trust and the custodian is governed by English law." Perhaps this is why the SEC, etc. doesn't do anything...it's out of their hands. here's the link:
iShares® Silver Trust The iShares® Silver Trust issues shares (“Shares”) representing fractional undivided beneficial interests in its net assets. The assets of the trust consist primarily of silver held by the custodian on behalf of the trust. The objective of the trust is for the Shares to reflect the price of silver owned by the trust less the trust’s expenses and liabilities. The Shares are listed and traded on NYSE Arca under the symbol “SLV”. Market prices for the Shares may be different from the net asset value per Share. BlackRock Asset Management International Inc. is the sponsor of the trust, The Bank of New York Mellon is the trustee of the trust, and JPMorgan Chase Bank N.A., London branch, is the custodian of the trust. The trust is not an investment company registered under the Investment Company Act of 1940. The trust is not a commodity pool for purposes of the Commodity Exchange Act, and its sponsor is not subject to regulation by the Commodity Futures Trading Commission as a commodity pool operator, or a commodity trading advisor. Silver owned by the trust will be held by the custodian in England, New York, and other locations that may be authorized in the future.