In many towns that are not the hotbed districts a good 8th grader (not even great) will benefit from JV ball. Doesnt even have to be playing against really good Jv teams.
You are right, there isnt much if any great JV lacrosse. many of the rising stars are brought up. But on the other hand, there isnt any good middle school lacrosse. This is where he would be. Between the putrid competition with the scheduling and the 5 quarters and the general lack of qualified or sufficient coaching at this level, the lacrosse sucks. Let him play faster with a longer season and better competition on JV.