There's exactly one middle school that's capped, Mills Park in western Cary. There is a new middle school opening up in that area this summer (it's a year round school), with a wonderful principal who used to lead Davis Drive Middle. It's called Alston Ridge Middle School.
Since your husband is gong to be working at RTP, you'll probably want to look at those schools, along with Apex Middle and Apex Friendship Middle (also brand new, just finishing up its first year).
I suggest contacting the PTA at any school you are interested in and getting a feel for the school that way, and scheduling a tour.
School for traditional calendar starts at the end of August.
Here's a helpful link:
https://www.wcpss.net/Page/33753
And yeah, middle school hasn't changed much. It kinda sucks.