I was talking about precisely this the other day with seraph. This would be helpful for people like me who like to curate lots of content, but prefer to be able to control how much power I put behind various posts. I do think there should be a cap on how much power can be used on any one vote though.
I believe 100% is the cap, and that's like 5% of your daily allowance, before you need to recharge.
Where would you place the cap? It seems fair to let someone use their full 100% if they'd like to.