Hi Timbo
I have no doubt that this lens will have to be a HUGE IMPROVEMENT of the lens it replaces. There are, at least for me, a number of concerns and it also brings a number of dilemmas.
Firstly, the MTF graphs indicate that this lens will be superior in terms of sharpness across the range - that is good; Secondly, the VR has been improved, so hand-held will probably be much better; it will still work (how well, nobody yet knows) with a 1.4x extender on the newer Nikon bodies, giving a reach of up to 560mm on FX and equilavent of 840mm on DX bodies;
The downside for me will be the price and I believe that your estimate of R25k - R27k is a bit optimistic if bought here in SA ..... I think you can expect R30k+
But here is the dilema .... What, if any, would be the improvement of this lens over a 70-200mm f2.8 with the associated 1.4x, 1.7x and 2.0x converters attached. Changing converters may be inconvenient, but you do gain the benefit of having a similar reach with a lens that has a fixed, and not variable aperture ...... and that is a huge benefit when dealing with the isolation of a subject in portraiture, AND you can save a chunk of change in the process.....
Personally, for an outlay of R30,000 for a lens, there are a number of other options that provide for a better solution, at least on paper for the moment.....