Old ball, new ball?

Here's a question that came up recently on Golf Monthly forum that sorts out the 'men from the boys'.
When you hit over water, do you take your usual ball, or reach into the depths of your bag for some old ball that you regard as expendable, i.e. the all too aptly named water ball?
The majority favoured the positive mentality of sticking with the usual ball, and very few owned up to 'changing down', but I have to admit I'm with the scaredy cats here. In fact on some holes, usually where the water is right in front of the tee and I'm reasonably confident of hitting over, I don't even think of changing, but there's always that pesky second. Not a long hit, but just far enough for the wind to accentuate that slice ... you can guess the rest.
In fact, thinking about it, there's water in play on a lot of our course, but there's only one hole where I habitually change the ball, so maybe I'm not such a wimp as I thought, or as I used to be.
The other disadvantage is that on those days when I sail across the water on the second to land plumb on the green, I'm stuck with the old ball for putting. Not that I think I have ever sacrificed the hole for that reason!