Well, for some time I had been grappling with WHERE to put static defenses near mineral lines. Should I put them behind the minerals? Near the gas? But I had assumed that putting them INSIDE the mineral line, where the workers would have to walk around them, would be a bad idea. Afterall, workers would just have to make longer trips back and forth between the minerals, and theoretically that should cut my mineral intake.
But I decided to run a quick test, and I found that the impact of buildings inside your mineral line can be nearly insignificant. In fact, with 3 properly placed buildings, the impact seemed to be less than a single worker.
Here's a video to demonstrate.
Now, the income tab in SC2 is prone to a lot of random noise, which can make exact estimates difficult. But by carefully viewing the range of numbers during each individual case, we can see that the impact of the pylons seems to be less than a single worker. 19 mineral workers with pylons actually yield a slightly better economy than 18 mineral workers with no pylons. The two pylons used that slightly impede probe movement near the gas seem to have no effect whatsoever, since probes already have a small waiting time buffer when a geyser is saturated.
With this in mind, is it worth it to build your static defenses inside your mineral lines when you're expecting harassment?