ADNS 3090 and varieties, which cpi are useful?

Let's start from the beginning making a chronological timeline, shall we?

S3688

---

>--- S3888

---

>--- A3090 ---->--- S3095

S3688 - Sensor present in DeathAdder 3G and Salmosa, tracked up to 1800CPI
S3888 - Sensor present in DeathAdder 3.5G, DA:BE and Abyssus, tracks up to 3500CPI
A3090 - Sensor present in Zowie AM, CM Storm Spawn, Zowie ECx eVo, Roccat Savu...
S3095 - Sensor present in G400, tracks up to 3600CPI

However, the differences don't stop here, as the A3090 "package" implementation has been modded many times :
S3095 is "more a less" a A3090 sensor with a custom lens and illumination package that make it jitter at high CPI.
Zowie AM and ECx eVo both have a custom Kingsys lens, so it has lower LOD, also lower max tracking speed and custom CPI steps.
CM Storm Spawn (afaik) takes the default package from Avago on the A3090, with the latest SROM and good firmware, but the sensor is rotated 90º.
Roccat Savu takes the default lens but it couples the sensor with an infrared light and it also gets rotated 90º.

So, as you can see, every company treats the sensor in a different way, and thus, achieve different results.

Answering your question, mice with sensors S3688, S3888 and A3090 with Avago lens should have no problem at all tracking up to ~2000CPI, and that's a conservative approach (S3888 tracks great on 3500CPI, and some mice with A3090 track good enough at 4000CPI), however G400 does have that characteristic that it tracks best at 400/800CPI and other native CPI offers do jitter a bit.

Pretty much every mouse will differ due to different hardware, circuit design, and firmware even if they share the same sensor hardware (which is the case).

LED quality is actually pretty important factor that seems to be overlooked in some of these brands without any true R&D.

Just noticed your reply.

A3050 sensor is a good entry sensor, but this means it's very decent at 500CPI/125Hz, and then performance gets worse the more CPI and Hz you add, as it's just weak - it can't manage high troughput.

As far as I remember (speaking from the back of my mind here), PixArt optical sensors perform in an acceptable way up to 1600CPI, yet tracking quality is a bit lower than A3090 but probably comparable to a A3050. I guess you would have more luck gathering info in the Kana/Kinzu v2 thread though

A long time ago I was told to lower a bit my sensitivity, that this way I would improve my aim. I did, over and over again, and now I'm at 60cm/360º. Watch out, it's addictive and at some point you need to stop and feel comfortable with your chosen CPI

It's exaggeration, 1800 CPI isn't as good as 400 and 800 but it's still good.