I was there once in the last week of July, first of Aug. We knew what we were in for, so we took pro-active measures and it all worked out. That trip we were staying at POP and made sure we were were at rope drop each day and back for a long lunch/nap/swim from 12-4, then went back after the rain stopped (thunderstorm each afternoon due to humidity). We also had camelback water backpacks that we filled with ice at each meal stop, personal mister fans, and those gel filled neck coolers. The crowds were intense, but we knew that going in and resolved ourselves to be patient and spent the extra time in line trying to see special details around us that we usually miss. EMH times, park hopping, and fastpass strategies also helped.
We were NOT all grouchy, tired, miserable, or saying "we will never do this again" though. In fact, it was one of our more magical trips. I think it is a change in mindset and planning, but not a deal breaker for us.