I've done 'em all and here's my take:
The tours you mention are all terrific and well worth it. (There's a new one, quite pricey, that I haven't done yet, but soon).
Backstage at Believe is a bit of a disappointment in that you are not guaranteed to see an orca. They can swim into the pool if they're so in their mind, but none did when I went.
What they do is show a half-hour video on a screen at the back of the pool. The kids aren't much interested, so they chatter away, which means that if you want to follow the video it's kind of hard.
In a way, what you're really paying for is good reserved seats at the Shamu show without having to show up 45 minutes early. Not the best seats IMHO, but pretty good, a little to the left of center in the upper section.
Now, the Dine With Shamu program does guarantee some face time with an orca, so if that's your goal, it's the better choice.
The food at both is so-so, but it's all you can eat, so if you're Homer Simpson . . .