Aw, c'mon deep...

Everybody needs a little diversification.

Well, maybe not *needs*....  :)

It is a good idea, though.

I have SSO.

I have one other PM mining stock (in the gold mining area)

I have "dabbled" in small amounts of other stocks (SPQ, which is on this site also, has been very good to me over the years)

Small investments in the Uranium sector. 

I also have investments in the Oil & Energy Income Trusts area.

(Which have also been very good to me, last year's Halloween "gift" notwithstanding)

But as far as Silver based investments go, I agree with you...

AG itself (in whatever form) and SSO seem to be enough for this sector.

Remember, with SSO, you also get some exposure to the bullion itself too (which they hold a few ounces of), so maybe just SSO is good enough in the AG sector.