Here is the way I'd look at it with your wife... true, magnetic ballasts are less efficient than electronic. However, magnetic ballasts often run the lamp better than electronic. The electronic ballast market is full of dubious marketing claims such as that the ballast "adjust itself to each lamp" and other such BS. If you look at electronic and magnetic ballasts compared side by side, the magnetic usually wins on lamp performance.
Magnetic ballasts are also MUCH less prone to failure, and if they do fail, it's usually a cheaply replaced capacitor. Electronic ballasts are usually potted in tar to prevent someone from doing any work on them, and even if they are not, can be dangerous to work with.
To touch a little more on the efficiency claim... you won't get much for the ballasts used... probably less than half of what an electronic ballast costs. The difference in efficiency between electronic and magnetic is there, but it's not a huge difference. How long is it going to take that small difference in electrical savings to make up the outlay of cash for electronic ballasts?
Don't get me wrong... if considering a new ballast purchase electronic should be a serious contender... but if you already have the magnetic ballasts, I don't think it makes sense to chunk those and go out and buy electronic for a marginal savings in power consumption.
