Se?or HTH John,
Such a formula is proprietary to a user. To another with different usage habits, such as twice or thrice the number of cycles in a given period, toss in a spoonful of "not recharging them all the way most of the time", a dash of "Well to tell you the truth the batteries may sit a week or so before they get recharged" and this really throws a monkey wrench into the calculations, at least predictability or estimation.
This point is the most difficult to address when advising about batteries of any kind or shape.
What works beautifully for one person may mean a miserable failure for another.
Now apply all this to "Is It Worth It?"
And an unaskable question meets an unansweable reply...
Add up all the pluses you can muster. Subtract by all the minuses you think matter. Roll the dice, throw salt over your shoulder and hope for the best.
What I can tell you is both types of batteries have very common issues. With one type diagnosis is one hell of a lot easier than with the other type. But again the values are proprietary. That's why these battery threads are seemingly endless.