It's partially because I have 3 blogs, soon to be 4, and we all vote each other, so this is part of the reason it works for me financially over 500. But it is also to have a higher vote on all my blogs so I can vote the people who interact with me for a decent vote. Most people I deal with and vote for are tiny fish and if I don't do it, no one will.
I choose not to go the delegation route of letting others do my voting for the most part - maybe later. I have not run numbers, but I am associated with people far larger than me who still lease.
I plan to do it until I am at 5000 sp in case I ever get that far. I was buying votes as you mention but stopped that as not being profitable at all.
I do not find keeping track of delegations to be hard at all. I am only sad when people pull them unexpectedly and this is why I am moving to 50 sp leases instead of 100, so that a loss does not hurt as bad.
I think it is an individual choice, @ribbitingscience. i want the biggest vote and biggest sp I can get while powering down. I find this works the best. If you have only one blog and do not power down your choices will be different. I still recommend it for all under 500 sp.