>>304225096
It's absolutely worth it. I own a 5k+ myself + I bought the Valve knuckles and base stations from their store.
The eye tracking module is meant to enable FoVeated rendering which increases your FPS by about 60%, more if you have an RTX card (no idea why).

>>304225109
Pretty good. The only thing that sucks about it is the strap it comes with. I'm using a Vive DAS + 3D printed parts to attach it onto the Pimax, but their own deluxe audio module is coming out soon.