I only know of the Classic Kong - have no experience with the Extreme. If Ruxin never tore up the puppy Kong, then I would agree with you that the Extreme isn't necessary. My b never chews on the Kong, just licks it to get the stuff I put inside. He did chew on the split antler I got him (with marrow exposed). I've started looking for raw beef bones to give him. I wish I could afford the "tomahawk" or "cowboy" steaks so I could cut the meat off and give him the bone. All I can find at a reasonable price are short ribs.
As for toys, I would get a squeeky tennis ball. It is sturdier than squeeky stuffed animals and he can run after it even if he doesn't return it. Treats in closed toilet paper rolls or even small cardboard boxes are my b's favorite - he gets to destroy something AND get treats.