I can't help you with Aleks, but I can speak to the times tables issue, FWIW.
We stopped using Singapore Math near the end of the year last year--though I think it is a good program in general and we may come back to it later--because DS-then-6 didn't have his multiplication facts memorized, he didn't enjoy trying to memorize them (speedy recall is SOOOOOO not his thing!!!), and the lack of memorization was making math painful for both of us.
We got to level 3 (A? I think? Though maybe B? I'd have to look, and I'm too lazy...), but it was just killing his love of math and we couldn't really progress further along the usual path without his knowing his facts.
My personal theory (with no evidence to back it beyond my own experience and general reading about child development) is that memorization of math facts isn't necessarily tied to GTness, and I'm not sure all 6/7/even 8 yos are quite ready developmentally to do that sort of memorization, even if they can handle the concepts intellectually. I think it's another example of asynchronous behavior: they can be ready for the concept of multiplication, but not necessarily the reality of it. I know this was true of my DS7.
Our strategy: focus on branches of math that aren't reliant on math facts. We did geometry to great success last year, and will probably do more this year. DH the engineer is also going to do hands-on physics/calculus with him: light on the equations, heavy on the concepts and the graphing. hopefully he'll pick up some algebra along the way, and even his times tables, maybe!
When he's 8/9 and most kids his age are learning their times tables, I will expect him to know them, too. We'll dabble in it between now and then in small, low-pressure doses in the hopes that he'll pick it up when he's ready. But I can't see a good reason to follow the standard path if it isn't working for him. Why? If it makes him hate math, then let's do something weird and concept-based that makes him like math instead! Then when it's age-appropriate--and hopefully my DS appropriate!--he'll learn the math facts.
That's the joy of homeschooling, right? Individualized curriculum! Even if it's really, really unusual!
