When investing, Im a big fan of diversification of portfolios. I believe that both Ethereum and Bitcoin offer value, albeit in different ways.
Even though Ethereum is positioning itself to become a large platform, the fact that Bitcoin is so well known makes it the first place where people invest.
I would say that diversifying is actually best when investing but, however, I don't think trading your bitcoins for ethereum is worth it. Bitcoin is already a big cryptocurrency itself, if you are intending to loose on your investment, trade your bitcoins for ethereum. I have nothing against ethereum but however, I just think that its not worth being traded with bitcoin. What more do you want? Bitcoin is getting recognised from everywhere in the world, it's most valueable than a lot of currencies. Why don't you just HOLD and HOPE?