HIVE to HBD you get half of it instantly as HBD, the rest after 3 days. For HBD to HIVE you only get the full amount of 3 days. I think that's the reason.
The danger of HBD to HIVE is that if price fluctuates too much, you could get an amount of HIVE back that trades for less HBD.
Posted via inji.com