You have a big portion of LTC in your portfolio. Maybe you may consider buying ETH with LTC (or with some of it) rather that with BTC.
Ether is a good hold. Every portfolio should have it.
I completely agree. Two crypto-currencies in the investment portfolio is a very low degree of diversification.
It is optimal to have 10-20 coins in your portfolio.
In this case, if even the price of one of the coins falls drastically, then this affects the total value of the portfolio not so much.