The warmest and most reassuring feelings! I purchased a model with a Red Switch, which has a very quick response time and was the first optical-mechanical keyboard. The only thing that I can call a "inconvenience" is this, but it's only for the first few days as I get used to everything. All of the drawbacks that I was warned about before making my purchase, such as "noisier than membrane ones," "heavy software for setting the backlight," and "unfortunate arrangement of Cyrillic letters," ended up being completely irrelevant to my experience with the product. To be more specific, if I hadn't read about it in the past, I probably would not have paid any attention to it at all. Printing it out and playing around with it is a joy! I did so for the 4020.