Although pegging is supposed to keep the value at 1:1, there is always a feeling that bit asset is not as valuable as real asset. Reasoning as follows. Feed price should be a good indication of current market price of bitshares. At external markets, when you sell at bitshares at market price, most likely you'll expect to sell at lower than feed price. On the other hand, if you buy bitshares at market price, you'll have to pay more than feed price. However, at the internal market, almost for sure you can sell bitshares at or higher than feed price. Of course, when you buy bitshares, you'll have to pay much higher than the feed price. Obviously there is difference between bit asset and real asset. Although it's hard to say how much difference there is, it is not hard to see that bit asset is actually cheaper.
One possible solution is to lower the feed price by maybe 1%. The disallows the guarantee of selling of bitshare at feed price, therefore increases the value of bit assets.