You'll associate it with any car you have and when you see your car without it you'll miss it and feel dissapointed.
It's also pretty decent as it legally says your name.
Also, imo, markets for them are very limited. Ok someone buys yours off you and it probably takes a while anyway, but in the future you may think, or be in the position to buy one again and I bet you'll end up paying alot more than you sold yours for. (A "DAZ" plate that is).
I've thought about buying another Williams for the weekend and immediately felt sad at the thought I don't have my old WMS plate.
Well, that's my feelings.