After BSIP42 was unvoted, magicwallet just use a "medium" price for months (multi sources include BitShares blockchain). Same as clockwork, there is no USDT in any sources. In these days, as BTS price in BitShares are higher than **many** external exchanges, it seems the feed price is low. Now magicwallet changed to use a "mean" price, it is slightly higher. However, there is no perfect strategy. As many external exchanges has faked volume, the following equation may be better:
mean( medium price of external sources , bts price in BitShares blockchain).
For these days, the feed price seems low, but it is health in my opinion: It is a warning sign to not just use MPA( which is derived from BTS) to bring BTS up. On the other hand, it is hard to be manipulated to eat the margin call to make profit as the market price is higher.