Whilst I don't understand all the math that is involved in this...

Whilst I don't understand all the math that is involved in this proposed transaction. I do understand that we may be paying a proportional premium in franking credits to Shell which is offsetting the actual purchase price per share WPL is paying. As you say "taxpayers on high income tax rates get a negative value [tax liability]", this may occur to some degree for individuals in such a situation in the short term. Those on a lower income tax rate may conversely be on a more negligible degree. One should probably speak to their Accountant for more clarification if one has a large individual holding and is on a high income tax rate. WPL state that this deal will not affect the DIV payout and from external analysis should leave approx $1.9B in Franking Credits in WPL's account.

On the upside this deal does get Shell's holding or rather overhang off WPL's back, which over the years I have been a holder has drawn many a lament/uncertainty from other holders. If I'm still reading this right, the deal also appears to leave the median to longer term situation in a possible (or should it be more accurate to say probable?) higher cash flow rate per share which would result in a higher dividend per share in future periods. Such being correct this may translate into a higher SP accordingly. From my present perspective, this would not be displeasing at all.