I would think that this would be difficult. The potential economic benefits would include avoidance of fines and avoidance of lawsuits if there were hazardous areas not properly classified. You might also find some cost savings possible if non-hazardous areas were incorrectly classified as hazardous.
The problem is, you can't estimate the economic benefits without knowing how many areas are mis-classified. You don't know this until you do the classifications. In other words, you might be able to determine the economic benefits of classification after the fact but not before the fact. Of course, after the fact, you have already spent the money to do the classification so it's hard to justify spending the money to estimate the economic benefits.
Suggestion: The technical aspects may include potential hazards from inappropriate classifications, such as explosions, downtime due to the lower life expectancy of the equipment, extra expense with equipment shorter life-cycle, life hazards and injury of personnel (and associated law suits), lowered insurance rate, etc.
The compliance with the standards is not only for safety of personnel but also for the appropriate life-cycle of equipment, lower insurance rate, etc.
