I am not aware of any differences in quality of materials between the FPV and the Thermal. I also don't believe that there is any significant difference between the original and the FPV in flying qualities. The same propellers are in exactly the same place, it is just that the legs don't have the projections beyond the props like the original. The big difference is the beefier legs which are definitely stronger and resist twisting better.
Since I already own the original, it doesn't make much sense to sell it and buy the FPV, which I have no use for, just for the stronger legs. However, in your case, it is a tough decision. Essentially you are paying an extra $100 just for the stronger legs since you won't use the goggles. Looking at all the busted legs on this forum over the last 6 months I would be sorely tempted to do exactly that, particularly if you are a new pilot.