many adults do well on the same stimulants that were poorly tolerated as a kid
We still use basically the same drugs now, even if brands and durations of effect are different, but some side effects are much less of a problem in adults - for example the loss of appetite that can really limit treatment in many kids. Other side effects we have learned to work around - like rebound irritability, anxiety and moodiness at end of medication effect in the afternoon (by adding a top up at lunch or switching to a longer lasting medication). We know more about the use of combinations of stimulants and non stimulants to reduce side effects, and frankly, we often get lucky and patients don't have the same problems, even with the same medications. Bottom line, there's a good chance you can do a lot better on medication as an adult.
The 'need' to be the class clown is less attractive to adults.
Adults are more aware of the need for strategies to remember medication which often makes it easier to get used to it. And adults are more likely to come back in and complain if things aren't going smoothly.
In practice, patients often do well with the same medication that was a disaster for them as a child so it sure doesn't prevent me from trying the same medication, albeit with some caution.