Hello!
Welcome to Linux Lite, and to the forums. I, for one, am interested in what you can share with us about security. Who knows? You just might end up with a sticky or few here.
I like LXDE as well, and it can be somewhat faster, but editing menus can get sticky with it, and was never able to customize it quite to my liking without it affecting something else.
With LL, XFCE Theme Manager makes the customization process SO easy. I also prefer XFCE's weather and CPU usage system tray applets.
IceWM is my fave super-light window manager, but it has a steeper learning curve. Over time, I've found that speed is inversely proportional to user-friendliness...
73 DE N4RPS
Rob