Some people can adapt to the sensor's flaws and be happy with it. Others can't be bothered to adapt to a defective mouse. Others will blindly support their purchase because they spent money on it. So it is hard to dig through the BS and get a good review. Try to get your hands on a mouse that uses the sensor and make a decision. If it turns out to be as shitty as some say then return it for a refund.

I personally can't stand mice that use the ADNS 9500.

Get a WMO and don't worry about it. Well... there's the whole low dpi thing, but it's better than a randomly responsive controller.

I've got a WMO and it doesn't feel as responsive at high speeds as a low senser. The WMO is a well shaped mouse no doubt but just I find the Xai to be a more perfect fit for me. And the button clicks are better also.

maybe u find the xai more responsive at those speeds, because there is indeed noticable accelleration. :P
(tried xai, and it definatly had pos. accel)

I have a G500 and G9X. They both have negative acceleration on my QCK. My experience with this sensor is that it's not good on black cloth. Whatever flaws it has is much less pronounced on hard surfaces. If you use a hard pad you'll probably be fine.

i got a xai and a qck, it's fine (imo).

the pos. accel kicks in around 1m/s, i don't hit that in game. i like the low lod and general "feel" of the sensor and prefer it to the other mice i own.

This is your last chance. After this, there is no turning back. You take the blue pill, the story ends, you awake in your bed and believe whatever you want to believe. You take the red pill, you stay in Wonderland, and I show you how deep the rabbit-hole goes