umm i got higher level in ghost then i did in maplestory, but i dont remember how long i played both or percentages n stuff imo it shouldnt really matter how fast you level in a game but the ammount of fun it gives =p
From my experiences with both games, I would say ghost has more grind than maplestory. Percentage, umm, idk, maybe around 110%-130% somewhere in that range approx.