I wouldn't sell, I also hold some ether and i believe a great future awaits for ethereum. However we should keep in mind that the total amount of ether is about 5 times bigger as the amount of bitcoins. This means even if ethereum would overtake bitcoin in market cap, the value of 1 ether would still be lower than the value of 1 bitcoin. I say this because when people say that ethereum is going to overtake bitcoin they think that 1 ether would be over 3000usd. But that is still along way off