After a day of use, I can finally give a review of the K90 keyboard. I will say that I'm thoroughly disappointed. Here's why:
First of all, my board came with the wrong keycap on the "1" key on the top number row. The key cap was the same as the key caps used on the letter keys but it was printed with the correct "1" and "!". This key is at a different angle than the other keys. The top of the key is on a different plane than the rest of the top number keys. This was the first noticeable defect.
Secondly, the caps, num, and scroll lock indicators don't work correctly in Linux. I've tested this on two of the keyboard. Neither work correctly. So you have no of knowing whether the number locks, caps lock, or scroll lock are on unless you type or test them out. This makes them useless in Linux. This was a major turn off for me.
Finally, giving the keyboard the benefit of the doubt, I decided to install Windows on my main computer and try it out there. The locks indicators worked correctly here. I downloaded the latest software for the keyboard and proceeded to upgrade the firmware on the board, hoping that the firmware would contain a fix for locks keys in Linux. However, after the firmware update the back lights on the board no longer function, the volume and other media keys don't function, and the macro keys don't do anything either.
With all of these flaws, I can say that this keyboard is pretty much not for me. Some people love it, but I've found build flaws in mine that speak of faulty quality control, and the software for the board is terrible. Why does the keyboard software control the functionality of the locks indicators? Every other keyboard I've ever used in Linux could handle this. I feel like there's way too much software dependency on this board. In order to use the macros you have to use Windows. Even old IBM dummy terminal keyboards had hardware controlled macros. If you are a manufacture of keyboard and you decide to put macros on them, make those macros record and save to the hardware itself.
The one thing that I was worried about when getting this keyboard was whether I'd like the Cherry MX Red switches that it comes with. These were great. They aren't what I personally go for, but they are great switches. The linear nature of them make them fast. There's little resistance for you fingers and I upped my WPM typing speed by 6WPM. I went from 74WPM to 80WPM just by switching from buckling spring to the Cherry MX Red switches. I think that my speeds would be comparable on MX Blue or MX Brown switches as well.
So, I'm sending this keyboard back and I'm getting a Rosewill mechanical keyboard with Cherry MX blue switches. I will probably order some o-ring dampeners from WASDKeyboards to go on the keys. That will make them much quieter. Sure, I'm giving up the back light by going to the Rosewill keyboard. However, I'd rather have a solid keyboard that works as it should than have a keyboard with a ton of features that don't work.