If the heat-shield is rattling it is NOT properly secured. I had mine secured and no more rattling.
The heat generated is substantial esp. if idling in traffic or if you have to a Dyno run for emissions testing or just fun.
If you can, I would keep the heat-shield, esp. if it only needs either more screws or bigger screws, or a little tack weld.
1988 360TE AMG