You asked if it was going to be worth it. If it's the only thing you're doing, and it sounds like it is, you're asking a great question. There will be scouts at the tryouts, so a kid will be seen whether they make the game or not, but most kids do NOT make the evening game. It's incredibly competitive and if a kid does make it, practically every scout at the Classic will be there watching. The tryout has a lot of stuff going on at once--some positions hitting, some running, some doing defensive drills-- so it's impossible for one scout to see it all. If your son were going to play with a regular team through the weekend, I'd say the academic tryout is a no brainer. I'm less likely to say that about just going for the academic game, though as you've read, people do the tryout by itself and find success. If I remember correctly, fewer than 20% of the kids trying out make the game, but my memory could be off. Anyone out there recall the rough numbers?
I think you're asking great questions about whether to go or not. I just want you to have accurate information.
My experience stems from having two boys tryout for both jr and sr events. Were both seen by several schools we contacted ahead of time during the tryout, but neither of the boys made the evening game. And if speed is one of your kid's assets be prepared for the slowest 60 time your son has ever had. They run it on a notoriously slow surface.
Good luck with your decision. If he makes the evening game it's the only event going on at the time.