Originally for me (& oldest son), above level testing & talent search were suggested by the head of gifted ed for our school district. I had a good rapor with her and said my 6th grader was bored and what could I do to help him. I was surprised about the suggestion and researched it.
I was not a great test-taker, but some people enjoy taking tests. My DH feels that way. So one reason for doing it could be "fun". A new experience. A challenge in the midst of boredom.
Since that time I see tons of value for doing it. First, like Taminy said, kids are test at grade level year after year and may max those those out. The above level tests give them a higher ceiling to see where they really are. For instance, a third grader scoring 99% on a 3rd grade test says one thing. A third grader scored 90 or 95% on an 8th grade test tells another story. You and your child can decide where to go from there with that information, but isn't it better to have it and know what you're dealing with?
Secondly, the tests give eligibility for online and summer program opportunities. Maybe you'll never do that, but they can be really cool, so you might consider it.
Third, like it or not, college entrance exams have a huge part in college and scholarship applications. It may seem a long way off, but it'll be here before you know it. With the other benefits outlined above, think about the cost-benefit of developing experience, comfort and high performance on college entrance exams. It translates to a LOT of money. My state offers full scholarships to state schools for kids scoring over a specific ACT score. I attribute some of DS's excellent scores to early testing experience. Merit scholarships are tied to high scores.
In the end, I say BOTH SCAT and EXPLORE. They are different experiences and offer a form of enrichment or at least a challenge, valuable information, experience, and can be worth the investment in the long run.
