RE:Variable dividendI never understood these discussions....
Buyback = zero sum game -> book value per share stays the same.
Buyback with debt= pay interest on the buyback sum -> makes only sense, if the company wants to go private, valuation wise it's ev-
Divi = zero sum game, but only, if you don't have to pay taxes on your divi. Here it's a bit more complicated....there are countries, where you can collect divis for free, but they tax realized gains and vice versa, so it depends.
Pay a divi with debt = makes no sense, except for the situation, that you're the holder of f.e. 70% of the company (=you can't sell in the market) and you want you want your money back and some...even if the company is overleveraged with debt and after that point "to hell with them" and unload your shares.