Corsair K90 is OK
My ergonomic MS 4000 keyboard finally wore out where several keys required banging multiple X to get contact. Doh! I needed a new keyboard...again.
I do game but wasn't sure about mechanical keyboards so I waited for a Newegg sale. In addition to the Corsair K90, I was also looking at the Rosewill, Gigabyte, and flagship Razer Black Widow models (? 2013). I needed back-lighting but didn't want red. I wasn't sure about what type of Cherry MX switches to get (but since have bought a sample pack of switches from WASD keyboards).
The Corsair went on sale first so I got that. Most keys are Cherry Red except F keys, G (macro) keys, and the insert/delete block, which are rubber dome. The software worked fine for me and the firmware upgrade was painless.
Pros:1) For those who are unsure, it allows side by side usage of mechanical and rubber dome keys
2) Allows gamers to see if they use macro keys at all since there are eighteen
3) great illumination of mechanical keys with bad illumination of rubber dome all side-by-side for your viewing
4) nice barrel type volume control and other nice media controls
5) robust braided cable without any micro-usb connector to break
6) feels good on the hands even after an MS ergonomic brand for years so Corsair must be doing some design correctly
Cons: 1) takes short time to wish all keys were mechanical especially the insert/delete block
2) takes short time to wish the nice illumination included all keys
3) cherry red mx can be a challenge to average typists so I may get a second keyboard like a Ducky Shine II for typing
4) cost - hard to justify $130 MSRP for a hybrid mechanical/dome keyboard but maybe sale price is OK for the "first mechanical"
Just my opinion. I think the K90 plays a role in moving into mechanical keyboards for those who are uncertain. Just wish they would drop price on the k90 hybrid and make a full mechanical with more choices for switches and colors for lighting. That would be fun. Happy hunting.