I am familiar with AYSO Ladera Ranch and have to agree they are definitely the most organized branch (in OC). I have volunteered and involved with other OC branch and none of them are even close to Ladera. I do not know about regions outside OC.
However, tryout is still a gamble. It is true that they have "neutral" staff grading the players but how do you rate them based on 5 minute shooting/dribbling, one on one and scrimmages? Even a few days of full day camp is not sufficient.
They rarely drop/pickup players after the first year unless the player quits voluntarily or other extreme circumstances. This makes sense, though, because you don't want to breakup the team every year.
If any of you would like to join EXTRA team, be sure to sign up the first year it is formed, U8 I believe? or when 7v7 change to 9v9 to 11v11.
After teams are formed, there will be only 2-3 spots/year at the most, unless there is a new team, new coach, etc.
Teams can also be dissolved for any reason (not often by I have seen a few, usually involving the coach) but it happens in club soccer too so this is not a criticism.
Generally speaking, a good dribbler, 1v1 skills will be picked by AYSO Extra. All-star is different and a lot more political.
Club tryout? just like others mentioned, it is just a marketing scheme to gather players, most will be assigned to Flight 3 coach (no assessment). I tested this theory with both my kids a few years ago. They are in Flight 1 at the time. We went to several tryouts, all clubs immediately send offer letter congratulating that your child is ready to join flight 3 soccer club.