I use the S/V (which means Sailing Vessel) for my address when I have items delivered. Mostly because it sounds cool
But I don't believe I see the S/V used on boat names painted on transoms. It seems more like an official Mr/Mrs type thing. For a placard that was to be hung I don't think you'd normally see the S/V in it anymore than an office door placard would have Mr John Smith on it.
However I don't have a huge history with this nautical stuff. I wouldn't be upset if any gift had the S/V, but if I was making my own I'd leave it out. Would be interesting to hear other's opinions on this.