Hi, Dottie,
They say that Destination Math is k-12 on the website. I just know that DS8 enjoyed the animated colorful Elementary Problem Solving I course and wants to take #2 instead of EPGY Accelerated Grade 4 math. I would guess that the algebra courses are what CTY uses also, as I've read that the algebra courses are "better" at CTY than EPGY. That probably means more engaging. But I have no clue.
That said, we need to decide on what to use for 4th grade math. Probably Singapore Math and Hey Math! combined. (I have to update that post, too - they do have accelerated math available) I realized it was a mistake to allow DS to do math exclusively on the computer. He needs to write, too.