Forum:FOUR Legendary warriors

So I'm a newb and somehow (ironically) I got two of the 4 star forms of the legendary warriors (I have Shock Bow Loch and Earth Knight Edea), and I heard there are the super mega rare forms (6 stars) coming out in the future. Are they really worth it? Should I keep them and train them? And does anyone know when the 6 stars are coming out?