That would be the best amount.
The new Lv. 8 is pretty nice and allows for some 1 card combo. Easy summoning condition for following turns and quite a beatstick as well.
The Xyz is really only for early monster negate and not splashable because it requires Lv. 3 Psychic mon in GY so pretty much only PUNK can use it.
edit: oh wow the extra deck is packed if I insert Demonsmith. Damn, man
Mr God Jackstar, the Unfathomable Abyss, the Dancing Stardust of Sagittarius, the Blazing Inferno of Frozen Hell, Second Principal Leader of Incomplete Brigade!