Nice catch on the JBL's. It's been a while since I've shopped for nearfields. It looks like the same type of high-excursion ("long-throw" in JBL-speak) drivers showing up in bass cabs are also making it into studio monitors.
I wouldn't worry about the rear porting on the JBL's either. The port location doesn't affect the way that the box couples to the room at all, since the bass frequencies become velocity waves (omnidirectional) just outside of the port. A front ported and rear ported cabinet will behave the same way at the same position, unless you are actually blocking a rear port and changing it's effective open area.