Food for thought.
F5 team decided between 0 and 1 degree angle of attack was the optimal downforce for the 818R with the GTC300 wing. Any more than a degree of AOA and the car would understeer excessively. The CFD data provided by APR says that at 80 MPH and 0 degrees AOA the GTC300 produces about 140 lbs of downforce.
Now, if you look at the GTC200 CFD data, you can mimic that level of downforce at 80mph with approximately 12 degrees AOA.
The GTC200 is approximately half the price of the GTC300.
I also checked the drag for the GTC300 at 0 degrees AOA and 80 mph... approximately 16lbs, and the drag for the GTC200 at 12 degrees AOA and 80 mph... approximately 13 lbs.
This is all based on CFD data and not mounted on the car, but in a vacuum, it seems the GTC200 is the more efficient and economical choice considering the amount of downforce available at the front of the car. Adding canards, extending the front splitter, etc. could increase front downforce and provide the need for the larger rear wing.
Reference:
GTC 300 CFD Data: http://www.aprperformance.com/index....sk=view&id=181
GTC 200 CFD Data: http://www.aprperformance.com/index....sk=view&id=342