The 3.5 days isn't so risky, because it cuts both ways: it can work to your advantage as well as to your disavantage. Savvy traders have long recognized this, and realize that on average they can rely on the mechanism working reasonable over time.

the median price is also moving much more now in hive since we dont have any sockpuppets giving wrong median price. back in steem it was much more profitable to convert.

During the time before the launch of Hive, I'm not aware of anyone successfully manipulating the median price of SBD on Steem used for conversions. I have no idea about how the mechanism has fared since that time, as I don't really monitor it any more.