Luke,

I'm certainly no expert in the matter, but it seems to me what with a longer leader your drop weight is further up-stream from your offering, thereby presenting the offering in a more natural manner as it drifts downstream from your weight.

Can't speak for summer run fish, as I have no experience with them, however last winter we did fairly well using leaders that were 18" to 36" when boondogging the Skagit.

MB