Sativa flowers usually produce less loose resin than indica lines, so anyone planning to make dry sift or bubble hash should set expectations accordingly. The trichome heads on many tropical strains are smaller and sit closer to the plant surface, which makes them harder to knock free with cold water and agitation. A few of the hash oriented comparisons on https://hazesativaseeds.com identify the exceptions, mostly Afghan influenced Haze crosses that wash surprisingly well. The flavour of a good sativa hash is worth the lower return for me, but it is definitely a lower return.