That's a good question ! I reckon it depends on how efficiently you are curating. If you've got some automated upvoting and back it up by manually upvoting most days so your vote power is normally around 80% or so, then I'd keep the HP in your account to boost your vote value. But if you aren't regularly upvoting, then it's worth increasing your delegation a little bit at a time and monitoring the effect. There's probably a "sweet spot" where you optimise both your curation earnings and your EDS project earnings (both EDSI and HP).