I don't understand. Sorry. But to me, their current school IS close by. Only 8 minutes away, one way.
Since your eldest child is more "dramatic" and concerned about switching schools now, again... he will still have that issue, perhaps, even when he has to go to middle school. And maybe he is tired of switching schools. Having had to do so, when he was in 1st grade.
Middle school will be, no matter what, bigger in population and campus size.
Ditto Victoria W.
You said your kids are doing well at the school they are in now, and you really like the school now.
In all neighborhoods, it is comprised of kids, who go to various schools. And in order to know the neighborhood/meeting families, it is not mandatory or necessary.... for a child to go to ONLY the neighborhood school. My kids' school is about 8-10 minutes away. And in our neighborhood, the kids who reside in it... all go to various schools. Not only the same school.
So the problem is: do you want your kids to go to Middle School with other kids & friends that they already know from elementary school... OR, do you want them to go to Middle school with other kids from their neighborhood??? Which they may or may not know?
Kids, ultimately, make friends from many places. Not only from their neighborhood.
Regardless, you can STILL.... be involved in your neighborhood and meet the neighborhood families, even if... your kids do not go to the neighborhood school.