I'm using my Logitech G500, replacing my older G5... I still have the G5, and it's shape is a lot better than the G500, but I couldn't deal with the jumpy sensor, if only there was a way to transplant the G500 sensor into the G5. I've had the G5 ever since the one with the cracked blue texture came out... Logitech, G5, all of that is gone off of the mouse, and the scroll wheel is even shiny!
Now as for the build quality, the G500 seams a lot lighter. But I love the weights, still doesn't seam as heavy though. Having tried the G9x, I can tell you that it's not as good as either of those, it's way to light on both clicks, and as I do have heavy hands, It really sucks always pressing right click everywhere, So I sold that to a friend, and used the money to buy a G500.
I'd post some pictures, but my camera is dead right now... and my phone takes really bad pictures.
As for my opinions of Razer, I like their products, but after buying a mouse before, a Keyboard, and another Keyboard ( Both BlackWidows ) from them all with problems, I'm never buying a razer product again. I've been wanting to try a R.A.T. 7 though, even though I'm quite happy with what I have.