Bests & Worsts Reviews from Amazon

I ordered this keyboard to replace an aging K270. I'm a video game developer and computer consultant so I need a rock solid keyboard, which is why I choose Logitech devices knowing they are solid, even at the budget level. Ive ordered this model before from a different site, and have had no problems, so when the old one started to ware out, I chose the same one. Ive had nothing but problems with the new one. Its weird. This new one wont work with the old ones receiver. The problem is, it doesn't have the orange gear logo on the bottom, showing that its part of the Unifying "universal wireless system". When I try to connect to it with my Unifying receiver using the special compatibility software, its detected as M510 mouse and then fails to install. The problem here is I cant use my better Logitech mouse or any other Unifying devices with the K270, or I will need to use 2 receivers, and I don't have any open USB ports, plus there's potential radio interference. I ended up having to ditch my other unifying devices and use the compact mouse it came with. As if that weren't bad enough; it has a horrible lag between key-press and screen input, making it impossible to write with for any amount of time (writing this took some patience). Here's an example; Ill be playing a shooter game and all the sudden the W key stops working and I stop moving forward. I try to hit the escape key, nothing. Then 10 seconds later it escapes. This bug pretty much indicates to me that its a counterfeit or at least an inferior transmitter. Its not the receiver, because Ive had no problems with the M185 mouse. I have full use of the mouse - to open a virtual keyboard and finish typing one click at a time. Its detected by the Unifying software even without the orange Unifying logo and never misses a beat with the new KB and receiver. I would notice any slight stutter in the mouse pointer. Its compact size is small for my hands and has a loud click, which is bad for in the living room. One other confusing thing: Its labeled MK270 on the box; so shouldn't the mouse be a M270 rather than M185? No such item exists. Why would they make 2 different versions of the same model? The only indication that its not the same is on the back and in 2mm fine print where its labeled K270 and below M/N: Y-R0042. My old one is a K270 but M/N: Y-R0015. Ive read in the Q&A; someone returned their Y-R0042 and got the Y-R0015 as a replacement. The main point here: unless you want to risk receiving the incompatible and buggy version, don't try this product.