I guess it depends on what role you would like ETH to play in your investment portfolio.

For the role of the digital gold, a vehicle for long term savings, a way to preserve value, I think there is no second best. Buy Bitcoin.

On the other hand, if you treat ETH as like a stock, a security, which by the way it probably is, an unregistered security, like a company, and you use ETH as a way to invest in this company, then it may be an OK idea.

If a small size, like you said, and you are okay with the risks coming from the fact ETH is not decentralized, not censorship resistant and has no guaranteed scarcity, and you want to bet on its price increase, I'd say it is, or it may be a valid idea, a small part of the portfolio part for risky stocks.

But even then, price of ETH is anyway highly correlated with Bitcoin price, do you might not get much more alpha from it.

Good luck with your investments.

And of course, I don't know your situation so I'm not in a position to give any investment advise.