Big fan of this one. If this is really gone, it is going to be a big gainer this year IMO. FLW is just so iconic for architecture fans. My dad is an architect so I am a bit biased on how popular it might be, but I think this can outperform Robie House long term - not just ROI but actual sale price.
We, and by we I mean my son, while my dad and I watched and sorted pieces, built this during Thanksgiving. Very clever design although I agree with your points above on some of the colors. My son is 6 1/2, I was surprised he had the patience to complete it by himself.