If I recall correctly the Aero used Sapim CX spokes throughout whereas the + version only uses the CX on the rear wheel's drive side.
This should make the + a bit lighter but not by much.
I really enjoyed mine a lot (regular Aero) but check the spoke tension before you actually start riding them, it can be all over the place and often way too low for best performance.
Excellent bearings once they're fully run in and everything is easily serviceable as well. Clever hub design too.
Personnally I'd go with the + as it is the more current version of the two but that's about it.