Hi,
that's more strange than before.
G43 and G41 share the same bios but have a different audio card.
According to MSI website, G45 is the same as G43 plus the fast charge for usb devices.
Anyway, let's make a list for anyone that will arrive to this post:
MSI Z77A G41 and MSI MSI Z77A G43 works with ESXi 5.1 (first build and latest patch) with bios version until V2.5
MSI Z77A G45 works with bios until V2.6
So, basically, as you said, no additional driver, no customization needed to be done on the ESXi.
I will add, if you want to use DirectPath, it's better to disable audio card and integrated graphic card (if any in the cpu).
I didn't test yet if with the latest patch, the USB pass trought is working now :smileyhappy: