Convert to STEEM vs Selling SBD in MARKET

Hi Steemians

I joined steemit a month back. I got some SBD rewards and decided to use it to power up my steempower. Not knowing the mechanics behind each of the options at disposal I decided to go for the "Convert to STEEM" option against the SBD I had. It took 3 days and what I got in terms of STEEM was disappointing (I read somewhere it calculates average price over a period of time - not sure). As can be seen below for 1.121 SBD I got 0.653 STEEM.

The next time I tried selling SBD for STEEM in Market and this time for 0.955 SBD I got 5 STEEM.

I see some of my followers are also using the CONVERT option; so thought of posting to make them aware of the other option.

I regret wasting some SBDs with convert option. Wondering if this option is meant to be used in some other way. I would look for suggestions from experienced steemians if there is a better way to power up. Until then MARKET would be my go to option.