I love the Grade System, so much. If would be hard to use Gald, because to be it would just look silly using Gald to transfer Gald, and you won't be transferring as much Gald, y'know. Although, I don't think I've ever actually Grade Farmed. Maybe a little bit in Abyss, but that's basically it. When it comes to Symphonia I have so much Grade that I would get everything I want in the Grade Shop, and then I would still have a lot left over.
But, I don't really get your post. You only use Grade to transfer things over to the new game after you're done with the current play through, and if you're willing to buy things from the Katz and such in some games. Sure your Gald accumulates over time, but so does your Grade the more you play the game, and you unless you do spend it on things like the Katz, then you aren't spending it at all and only losing it when you get negative grade (which to be quite honest because I'm always underleveled I tend to only lose it during boss battles and the occasional normal battle).
Also, I don't know if you can do this in Vesperia, but in Abyss and (I think) Symphonia, you can put on your best weapon, put the game on highest difficulty, then go to the first area of the game and fight the monsters there. You won't get a lot of EXP (if you're really that concerned about it), aaaand you'll get a lot of Grade because 1 hit KO + Difficulty level + quick battle = lots of Grade.
Also, you can always up the difficulty or hinder yourself in some way (like putting your people on weaker levels) if you want the final boss to be less of a joke. There are people who get to the max level (255) before beating the game. Truth me told, I've only gotten my characters up to level 100-101 because I dislike grinding of all sorts, but over time I've been able to accumulate enough Grade for what I need for my next game (and now I don't even have to bother anymore when it comes to Grade).