First, I wanna thank everyone who created/updated this really cool mod. You guys are awesome.
I tested it today on 1.8 and it worked fine but I still have the hud displayed on screen in addition to my G19 LCD. Dunno why it happens since I had no problems with the 1.7.10 version. Here's what I used:
Magic Launcher 1.3.1 (Mod loader/Manager, I use it to launch the game instead of the normal launcher)
Forge 1.8 - 184.108.40.2060
Minecraft Logitech LCD Mod 0.3a MC1.8
Also here's a quick tip for those who have both a G19 and a G13 (works on both the 1.7.10 and 1.8 versions):
The app seems to always give priority to the G13 display instead of the one on the G19. I couldn't find a way to make it display on both at the same time so if you want to use the G19 LCD, simply unplug your G13 before you boot everything. Once the app is connected to your G19 LCD you can plug your G13 and the LCD used will still be the one on the G19.