1. I dont see the reason why you use
render wrote:Transmission: .8r .8b .8g
on the material? Its totally pointless since it adds a kind of absorption, without doing anything else.
2. Why glass and not glass 2?
3. Who says you cant use an IOR-gradient? For glass just use the gradient texture (uhmmm - ofc, why not?), for glass2 either make your own cauchy values for a smooth transition or sellmayer or tabdata...
Sorry I dont get for which problem your approach is a solution since your basic assumption (gradient IOR is not possible in luxrender) is wrong.