How can you say a weld in cage increased the value of the car? My experience has been that weld in cages mean that the car is effectively a full time race car, which limits the buying public interested in the car to effectively race only.
Secondly, i have found those wanting a dedicated track car with a full weld in cage typically like what they like and when they see a car with a certain cage, they often dont like the cage and would like the cage design to be different. Again, limiting the range of appeal the car has.
So, not saying you are wrong, just shringmy experiences