Ok, thanks to you wonderful people, I just had an HaHa moment...while in the shower lol.
I recall when DS was in PS 2nd grade last year, he said, "Billy is getting smarter b/c he can now do his math facts in 3minutes." So he definitely equates smart with being faster. I recall then saying that many mathematicians are not fast at computation b/c I didn't want him to think that kids that aren't as fast, aren't smart. He definitely has shut down in all areas since January after realizing he lost a lot of his times tables and it was taking effort to do 2-digitx2digit or 3digitx2digit problems.
As far as ASing. It really depends on the kid. We have always had math as a part of life, and science as a part of life. It's who we are (several Ph.Ds in science in the family). Also, our district's math program is not great and since DS wants a career in science (yes, he might change his mind but he might not, I never did change my mind), he needs a strong math foundation. I used living math until K/1 when he complained of math being way too easy and wanting more challenge and asked me to teach him. So we've done Rightstart A/B, C, and are now finishing up level D. These programs generally take 1-1.5yrs to complete - it's very conceptual. He typically does each level in about 6months time. We did 2-4 lessons per day of Level D while HSing to get him to the right level.....when we hit the right level and it now required a smidgeon of effort, that's when he shut down. This is a valuable life lesson for him.
Now his younger brother was even more mathy. He started adding and subtracting mentally just before and after 2yrs old. I started Rightstart with him at 4yrs old. He did level A, and has just finished level B as a 5yr old. Each level taking him only about 5months to do. The challenge level has been PERFECT! neither too hard or too little. I never really felt like I *taught* DS8 any math, I went through the motions. At times I feel like I'm teaching DS5, and I have to remind myself, that he is learning work ethic. He might think the first 3 problems are hard, and then it clicks and sails through all the rest. I soooo regret listening to those that told me not to afterschool DS8 b/c he'd be bored in school. I didn't, and he was bored anyway. SO over the 3yrs, his brain muscles atrophied. I'm now trying to build those up again w/ HSing.
Granted, I never forced them to do it. It took a backseat to homework. now if he didn't want to do math b/c he'd prefer to sit and play computer games for an hour, that didn't fly. But lessons were only 10-15min so I figure, that's doable.
Chemistry and physics... well the kids don't consider that schooling.

parents don't think twice about having little Bobby doing soccer 2 days/week, football 2days/week, and hockey on the weekends. But teach your kid something academic at home and eyebrows are raised.