I also owned it as a kid and never owned Zelda. OOT was my first Zelda game.
Deadly Towers is pretty rough though. Maybe I'll come back to it one of these days.
Like a big dweeb I was reading through the Spring 1993 Enix newsletter Warrior World and stumbled across an offer for mail away posters. Does anyone know what these are?
Also, it appears Dragon Warrior II and III were rare back then.
I think it depends on your goals. If you want it as a nice display piece, or to preserve it, get it graded. If you are looking at it from a monetary perspective it's probably not worth it(niche item).