When it is a matter of teachers or sports I think there is no question teachers 1st!
As for growing the sport, well we all have different opinions on that. IMHO, if you think club soccer will "grow" the sport beyond where it is now I think you are on the wrong track. How many friends and neighbors come out for your kids club games on weekends? (pretty much none!) The only people I see at the complexes every weekend are the same parents with the players brothers and sisters (sure a friens once in a reare while but come on).
School sports bring out the school and community. No, I know soccer does not turn out like FB but, if we promoted the sport/teams better (like Friday night games!!!) we could build a better fan base.
The teams at the middle schools are doing as much or more to grow the sport in the local area than the clubs are in the area of raising awareness amoung the kids.
As for "marginally talented players" both FMMS and GHMS took it to 3A and 4A JV teams in IRMO. There are highly skilled girls on both those teams who are improving the skills of the other girls by playing with them. Many of the 7th/8th graders would never make JV, and then by time they get to 9th they would likely not try out again or not have improved enough to make it then. The benefit to the HS program is that over time they get more players who have more playing time. Also consider that as more kids see middle school as a sport they can play the more likely they are to play rec/club soccer to help their chances of making the school team.