I bought the MMO7 a while ago (similar mouse, a few more buttons, ect...). All the Mad Cat mice share a flawed design. All the Logitech mice I've owned have a notch near the thumb that you can grip, allowing you to move the mouse with your finger tips and pick it up (as many gamers do to re-orientate on the fly). Mad Cat mice have nothing there, so trying to use the mouse under normal gaming situations means you're always hitting the thumb button or the mouse is slipping out of your hand. Also the lack of proper thumb grip means you end up squeezing the mouse very hard, causing fatigue to set in very quickly (1-2 hours of web-surfing using the Mad Cat mouse felt like 10 hours of hardcore gaming on my Logitech). If you're a 'palm grip' type with a smaller hand than this mouse may work great, but despite the numerous adjustments on it, it has some serious limitations. Don't buy this mouse without physically trying one out.
I have a R.A.T 7. Made it as wide as possible, as long as possible and as heavy as possible. Best mouse ever. I can never return to something else. The only problem is that occasionally the laser falls asleep and refuses to wake up (problem might be caused by poor soldering, but also the fact that it is a Philips TwinEye which is very famous for "good quality") so I have to replug the mouse. The design is great, nothing ever fit my hand until I got this pesky little rodent. Acceleration and tracking are flawless ( except for the above mentioned problem ). Drivers are still poor and I had few problems, contacted their customer support. I was not expecting them to answer. They were nice and all, but still, better not to have to deal with customer support. I do 3D modeling, visual FX and when I am too lazy to get the Wacom out, I even Photoshop with it. Usually after the 8-10 hour my hand starts to feel the strain, many details require to move the mouse with parts of a millimeter. Since using this mouse it's gone. I has been almost an year now, I hope it lasts long. Great design, amazingly comfortable, but has it's tradeoffs. As much as I love it, I wouldn't recommend it ( until they fix the driver issues ).