But there's also the problem of how the computer display reacts. It's not
linear ... the change from 0/0/0 to 10/10/10 probably won't be visible;
the
change from 128/128/128 to 138/138/138 will be quite obvious.

And if you should plan to print your presentation, keep in mind that Gray is
one of the most difficult colors to print on office laser printers. The one
in our office prints a blueish shade (though we compared gradients on a
variety of models before purchasing - this was the most acceptable one), but
I've also seen greenish and pinkish grays. And the gradient might not be
smooth, either.

Best regards,
Ute