I have another problem using G15 & octopus
i have following keybindings on the G15:

Logitech G15:
=============
a d f
g h i

j k l
m n o

p q s
u w y

m1 : alt + shift
m2 : ctrl + shift
m3 : ctrl + alt

but when i'm using the G15 keys, my main picks up the key that was pressed without the alt+shift or the ctrl+shift, so my map may open when i'm healing my hunters pets and such
quite annoying, but no idea how that comes.