RC, I am making the same point as you.  No need to beat yourself up for not buying certain cars, because back then, there was no way for you to know 100% that it would turn out as a profit and not endanger your family.  

For legitimate business purposes, the GT3 is equally practical to a 911 GTS.  Long as you have folding seats, can fit a lot of boxes back there without the rear seat. :D  That is why I think the dichotomy between the two cars for tax purposes is somewhat false, but the line must be drawn somewhere.