How do you use X effectively?

This has been more or less my experience as well. I do occasionally use the large shield boosters on my front row ships, but they really only make sense when you use a bunch of shield repair drones with them. Unfortunately shield weapons in general are pretty poorly balanced, so shield based defenses like I just described aren't too practical. Most modules are better than they were before the update, but they need a lot of work before being truly balanced.