delegating sp for the most part, benefits the community around you. the people you upvote get rewarded more. and there is a certain amount of social proof. When someone sees your 3c upvote they are often happy, and will become more loyal followers. it's very helpful to upvote the comments on your blogs and reward the people who interact with you. this is more of a long term investment, because some of these people will grow and you never know when they will power up and become a dolphin or a whale overnight because you encouraged them with upvotes. I see delegation leasing as a primarily benevolant act. however, there is a lot to be said for the social proof aspect, and the fact that, yes. people pay more attention to you if you have a higher sp, just like rep... maybe it doesn't really affect anything in a controlled study type of sense... but it definitely has an effect on the community around you.
if you are more short term profit driven, then you might want to try the "sell your upvote" feature.