I have tried the freezing method, blanching method and drying then rehydrating method and find the shrimp graze much quicker on the blanched leaves. I have tried the different methods on 12 tanks with various breeds /types of shrimp -cherry, crystals, TB ,Tigers and hybrids. I pick fresh and blanch them then freeze any left over. In autumn I pick the leaves before the tree drops them all and blanch and freeze them for a winter supply. The shrimp will devour them which ever way you serve them but the blanched leaves definately get eaten quicker than the others.
If you are going on holidays then a mix of blanched and a few dry leaves will break down over a different rate of time giving the shrimp food for a slightly longer period.