I do not fully agree but I believe that the investment in your hand should be 70 percent bitcoin as 30 percent altcoin. If you make your whole investment as altcoin or bitcoin, you will miss many opportunities.
That's what I would say too. And considering this is posted back in May, it looks like it could have been a pretty reasonable strategy. I don't know the total value of all alts vs. bitcoin (is there an index somewhere that we can see that?) but I think that overall alts have been losing pretty badly against it lately.
Now that bitcoin is gaining and alts aren't, I'm looking to get into a few alts a bit now. It's better to buy them while they're still low, because once they start moving, they really go fast.