I think it varies greatly based on the specific condition and your circumstances. It's quite possible that some are closer to tradeoffs than unmitigated negatives, while others aren't. The positive/tradeoffs view seems to most actively be argued by high-functioning people with Aspergers, and considering that many do contribute quite interestingly to society in ways they might not have if it were "treatable", that's at least plausible to me. That's still consistent with considering ADHD to not be of those cases.
Another way of viewing it is that there is a dispute over where to draw the line between "normal human variation" and "mental illness". People agree at the extremes: there must be some variation in personalities and cognitive styles that is not mental illness (e.g., introversion is not a mental illness, but a personality trait), and also some that seems pretty clearly "ill" (like some kinds of psychosis). But where between them to draw the line is less obvious, which is why psychiatrists get together every few years to debate it in a revision to the main diagnostic manual. Besides Aspergers, one active area of debate within psychiatry at the moment is the paraphilias: is being into S&M a mental illness, for example, or just natural variation within the diversity of sexual preferences?
Another way of viewing it is that there is a dispute over where to draw the line between "normal human variation" and "mental illness". People agree at the extremes: there must be some variation in personalities and cognitive styles that is not mental illness (e.g., introversion is not a mental illness, but a personality trait), and also some that seems pretty clearly "ill" (like some kinds of psychosis). But where between them to draw the line is less obvious, which is why psychiatrists get together every few years to debate it in a revision to the main diagnostic manual. Besides Aspergers, one active area of debate within psychiatry at the moment is the paraphilias: is being into S&M a mental illness, for example, or just natural variation within the diversity of sexual preferences?