My 16u son attended a TPX camp last fall. We've been to several showcases and this was well run, well organized and the college coaches they advertised as being there did in fact attend. The first day was drills and skill evaluation. 60 times, arm strength, hitting, etc. The second day consisted of a controlled game situation. Received written evaluation at the conclusion from the college coaches. OldDude son has received letters and calls from some coaches that I attribute directly to the event.
Now, does it make sense to send a 7-9th grader? Another question; but the one last fall did have a couple of sophmores. They were generally overmatched but likely good experience for them.