The notifications on resizes are required or gtk+ (and gtk3 as well) will either not resize or lag internal updates etc.
Qt is not affected, TK needs the notification when leaving the move.

On the other side it's not required at all to send them when just moving w/o actually XMoveResize  the window (apparently TK gives a shit on the geometry in the notification, but only wants a trigger to then look up the position via Xlib or whatever it will do there) and i'm willing to risk to say: also not when moving otherwise (but only once when leaving the move)

I tested a bunch of clients, like XMaxima (TK) gtk[3]-demo, chromium & google earth, wine/notepad, some sdl games, mupdf (probably no toolkit), xterm and gvim (aside kwrite, qupzilla, dolphin and whatever else i've open anyway) but would llike to know and test some extra smart client actually reacting on move events (by altering it's color or moving around some transient or so) - just that i don't know one :-(

Tested FF (Xul) and LibreOffice (UNO)