Pros: This mouse manages to deliver everything and not fall short in any individual aspect. The buttons feel great, light but not too light, stable, comfortable to press (middle click was especially important for me). The shape is great, although I have big hands and a fingertip grip so it matters less to me. Battery lasts a long time. Tracking is smooth and fast. Software seems to have improved (compared to like 10 years ago when I last owned a Logitech), and I'd describe it as pretty straightforward, easy to use and not annoying.

Cons: The only think I'd tweak is to have a snappier/clickier mouse wheel turning action, but that's a very delicate balance versus turning resistance. It's at a pretty decent point already.

Overall Review: Yes, it's expensive, but for people who don't want to compromise like me, this is it.

Pros: It was the cheapest available. Looks pretty good on the outside.

Cons: Installation was fairly painful. The screw holes on the sides weren't appropriate for the rails I needed to put on them to install them in my case. Not enough clearance under the 3 pins for the 3-pin connectors, the little plastic tabs that are used to align didn't fit. Construction appears very shoddy. You get what you pay for in this case. You only get a few shots at pluggin/unplugging the input molex before it snaps off.

Overall Review: The LEDs are way too bright. It's completely nonsensical. Why would you put insane 1-Watt LEDs on such a trivial component?

Pros: They move air. They come with 3pin to molex adapters. They were dirt cheap.

Cons: The molex connectors were SUPER HARD to connect. Some pins were badly aligned with each other, probably. I'm lucky I didn't cut myself on a sharp metal edge or rip some cable out while trying to push them together.

Overall Review: Not as silent as I expected at full speed. It was tolerable, but I preferred getting a fan controller for them.