i think you should convert the price into dollar to know if altcoins real bleeding or not. If not, then just hold your altcoins and buy more if you want.
If you are already down 20-50% this would really hurt as you would have to realize that loss to convert to USD. Better to hold for things to go up. Now if you are still in the green then this may not be such a bad idea in case the coin drops more you can repurchase at the lower price.