The more SP you have the more you get from being a curator. Inversting in SP means you are wasting all the dollars you would normally get NOW by investing in a long term bigger profit. The only advice I can give is don't turn your STEEM dollars ot STEEM POWER to plain STEEM, unless you really need to convert it to BITCOINS.
RE: DON'T USE 100% POWER UP - You Will Lose a Lot of Money