at 50/50, there are steem bid dollars being produced, and you get a part of the steem and the voter also, so the inflation grows, there are more dollars in total but the same usd value to be paid, so steem gets less valuable, meanwhile power up 100% you only get influence power, no dollars are being created on the spot but you can later upvote your own posts and get more sbd. I could be wrong but I still prefer power up 100%, get more influence power. There is only a minor difference between the 2 but advertising yourself, getting your post out will definitely get you more sbd. I don't currently have time for that, but if you found this helpful I'd be hapoy if you resteemed my post to let other know how to help steemit.