In the fps area of Quake 3 Arena I was pretty active. I became a real nerd for gaming mice, as for me it made a huge difference chosing good euippment, at a time when ball mice were still a thing and the first serious optical gaming mice began to surface.
So one day I gave the Steelseries Kinzu a try, as it was hugely advertised and was apparenty used by some very good players.
I was hugely disappointed with what I got. The Kinzu performed way worse that any optical mouse I used before, which were not even "gaming" grade (MS wheelmouse optical) and I could not figure out why. At the beginning I looked into possible software or driver issues. Did not fix it.
So I searched further and found forum entries that described what I was experiencing pretty well: for slow movements, the kinzu got positive acceleration, meaning it adds unwanted pointer movement to your mouse movement in an counter-intuitive way. But at faster movements, it would have negative acceleration, meaning the pointer was lagging behind your mouse movement. Then, there was an early malfunction speed which I would easily hit, where the optical sensor could not register movements faster then a certain speed at all.
I checked this myself with a mouse testing program called "Enotus mousetest", which was just released at the time by another mouse enthusiast.
So, I emailed steelseries support: Then began an oddysey over the span of a few month, of super slow, generic replies at first, then plain refusal to admit any issues with the kinzu mouse, then denial of giving my money back.
The offer they made was, I should send the mouse at my own expense to their nordic headquaters (which was like 20+ euro just shipping) and they would send me a replacement, basically the same mouse new. Which I was certain from other users also, would not fix anything, as the mouse firmware itself coupled with the optical sensor was the culprit.
I was young and naive then, I know now that it is common for companies to have such practices in the name of profit. Just that steelseries was the first to advertise as perfect and flawless and whatnot, with premium price, then delivering a really low quality product riddled with issues...
Funnily enough, similar happened with kinzu "v2" they released after, then "Xai" which also had issues. I continuously read the same complains, they never released a satisfactory mouse, did not admit or refund, but always charged premium price. It saddens me to this day I had opened pandoras box and had to understand what capitalism does to companies.
I never bought any steelseries product again, but to this day despise their dishonest approach.
The end.