Like Andrew I find having both on the table wastes so much space, it's rarely worth doing. The Rotary table is usually the wrong way round too; horizontal when I want vertical and vice versa.
So, unless I've planned a work-sequence specifically to use both, which is unusual, the rotary table is normally kept in it's box. As always much depends on what you do in your workshop. I suppose 75% of my milling is done in a vice, 10% rotary table, and the rest on a angle plate or clamped direct to the table.
Apart from keeping the ways clean and gently oiled, I don't worry about wear except when grinding or machining cast-iron. The machine only has to last longer than I do!
Dave