Well if it works nicely who knows, might be a real option for those that want V6 power without the drinking. As long as you're on top of cooling I don't see why it should be a problem - that mahoosive radiator sure isn't going to run out of cool water. But turbo engines do run hotter, so I imagine that the stat aperture will be greater most f the time, that's all
.
The quibbling about the gears is just icing on the cake really, if I can squeeze a bit more fuel economy and quiet out of it then that's a big bonus.
It's a shame the V6 IRD won't fit the manual gearbox as that would give you the ratio change you are after. I don't know if the internals can be swapped or not??