OP there are a lot of myths that go around about ADHD medication. Ultimately I would speak to a doctor, not go off random advice on the internet. But essentially your concerns are very normal and if you do get your DS seen by a professional then they would be something to discuss directly with that professional. A diagnosis is after all not an order to medicate :) It would be about whether you, the doctor, and DS (if appropriate) think it would be a useful option/tool for him at any time, which for some people it is and some people prefer not to use it. Ultimately, if he is struggling, it seems counterproductive to completely write off the option of something which might help without actually discussing your specific concerns - you could explain the history of what happened with your DH for example - with a medical professional with the relevant knowledge and experience.
These medications have been used quite a long time across the pond so there is good info on their longer term effects. You should also discuss the addiction issue, because there is some info that suggests it is ADHD itself, rather than medication usage, which precludes people to higher risk for addiction and that where children are successfully medicated before the teen years, this risk reduces and is comparable to the average population level risk of addiction, so it might be really worth exploring what your doctor thinks about your DS's individual risk profile WRT trying or not trying or avoiding as far as possible.
One problem with waiting and then trying to start medication only when you encounter more serious problems is that you then sometimes get the issue, especially if you're entering the teen years, that the problems which have built up so far create a level of resistance and self-doubt and have reduced trust between the child and adults in their life (teachers, parents) so they can then be resistant and not want to take them, just as they need them the most. Whereas if they have been seeing them as a helpful thing from earlier on then it's not so much of an issue for them to continue later.
OTOH, teenagers are also more independent and more able to make their own decisions about treatment and if medication has been something that they have actively chosen to try, then they are more likely to comply with the doctor's instructions of how/when to take it. Sometimes they genuinely do not need them earlier on and it makes sense only to look at more support when they actively need that support.
I do think the approach for this has changed a bit recently and I think this is positive; when DS1 (now 14) was first diagnosed aged 10, we were given leaflets about medication (though advised not to medicate at that time) and the advice in there was pretty bad IMO as it seemed to suggest quite an old fashioned, top down approach of "Just tell your child the medication is to help them focus at school". I've never taken that approach as it did not really sit right with me; when DS did start medication he was 13 and I felt it was just as much his decision, not mine, though I have let him know what my thoughts are. I wanted him to understand what it actually does (it does not just magically give you focus - I gave a simple explanation of the brain chemistry).