The upside of the weight/flywheel ( it's not a "balancer" ) is that as BKDavy posted, it makes the engine idle far more reliably... something which is very good for a beginner.

The downside is that you often end up adding weight to the tail to offset this.

As you progress to the point where you've removed all of the training aids, you could/should pull off the nose weight/flywheel. Doing so means that you can then pull off any tail weights...

This dropped almost half a pound from my plane.