Blizzard marketing going for a cooperation with Logitech is one thing, but Blizzard customer service still needs to police the game. That is why there are two different messages from Blizzard. One is pretty pictures the other is keeping the peace on the server.

As long as you do not abuse the G15's to run a bot program in it, which is theoretically possible and do not make any obvious or very long timed keyboard macros with the keystroke recorder you should be fine.

Example: A G15 macro that does 1, 2 sec pause, 1, 2 sec pause, 1 is of course against the ToS. It is detectable if your keystrokes are ever analyzed, but otherwise indistinguishable from someone regularly hammering 1.