Yes, I'm close on the current Radiance.Other than native 4k, I think you are describing the currently available Radiance.
Either way I'd be interested in such a device described by the OP, but not at the price point posted in above quote.
I use the 2143 and I'm very satisfied with! That's why I named it "midrange" device, positioned between the above discussed "LUT holder only" and the big "Pro". So I'd welcome a LUT holder having my listed features again - even with 4K out and in.
And to be honest, I can't believe, that a 4K capable "LUT holder only" box would be available under $ 1500 - as Jim wrote on Lumagen forum, already the FPGA costs more than an entire Radiance Mini-3D.