Absolutely must have, even if you have a light RX as I do. The inserts themselves are of very high quality, with ball bearing detents, crystal clear lenses with a nice coating that warms the image of the 8KX, which runs on the cool side out of the box. I was skeptical going into this due to the alignment issue with the 8KX (Pro-tip, completely minimize the physical IPD of the 8KX, even if you have larger IPD, which will make for a much clearer image as due to the canted lens design of the 8KX the stated IPD does not properly align with your actual IPD) but WOW, literally night and day difference. In terms of the improvement in clarity, it feels like I upgraded from 1080p to 1440p and I have a light prescription!

There are some caveats that must be pointed out however, seeing as how nothing is perfect. I had to switch from the thin factory facial interface to the thicker one as with the thin interface I could feel the RX insert on my forehead.

The lenses are tinted, but as I stated, it warms the image nicely.

I find that running the lenses on the completely lowest / closest together adjustment setting is best as any further apart and the inside of the lens frames will be visible in your peripheral vision and to my eyes there is zero difference in clarity moving the inserts further apart.

Room for improvement:

If it is physically possible to remove the lens frame on the sides of the lenses that straddle your nose-bridge that would alleviate the issue above.

Overall 5 out of 5, thank you Reloptix!