Is this a good or bad idea? What are the benefits/downsides?

 

What year/model? On an FD, it is an absolute must. The stock pre-cat just keeps far too much heat under the engine bay. An FC, this isn't as big of a deal.

 

Profile says FD.....so yes remove it. In addition to baking everything crispy (vac hoses, solenoids, plastic bits) they have been known to collapse and take out the main cat down stream. That can damage an engine.
They also do little for emissions...mostly just cold start.
Replacing it with a decent downpipe is both a reliability AND a performance mod.