^ That is pretty much what I said when I first read over the GTX series compressor maps, the only one I held any hope for was the GTX3071R on the premise that it should be able to perform similar to the GT3076R in most cases with a little more transient response from less inertia, though as it turns out from testimonies from people who have drive GT and GTX equivalents, the response actually does reduce a bit meaning even that may be a bit of a waste of time.
On the flip side, I have heard of some really impressive power results from GTX3582Rs when more exotic fuels than run of the mill gasoline are used - so if one was going to head down that path, they could show some worth there. I've still not seen any results from a GTX30-series turbo under real duress, but maybe they could still have surprises up their sleeves.