I noticed some conversion issues myself. I thought I'd put .2 bitcoin into steem, so I did a mock purchase on steem itself and on poloniex both for that amount. When the estimates came back from each site, poloniex paid about 5 more steem than steem itself.
Needless to say I purchased them on Poloniex and transferred them in instead.
looks like I'll have to look into doing something like that. I'm in NY so I can't use those exchanges, I think I have to use shapeshift. I would rather have the additional 30 or so coins then to just throw it away because of the poor conversion rate.