Earlier, I said I'd post back with my thoughts on the Logitech M500 "corded" mouse.
I've been using the m500 for a few days (on a secondary pc), nothing really standing out as exceptional or unusual with it. It's only a mouse after all. The cord didn't get in the way, I didn't accidentally keep hitting the right button, no real complaints anywhere.
So, it didn't have me doing cartwheels around the room with excitement. But...
I've just come back to my main machine that uses a wireless Logitech MX Revolution which now feels horrible in comparison to the m500. It's like using a brick. The weight difference is immediately noticeable, so much so that I've ordered another m500 to take over the mouse duties with my main/work pc.
Admittedly, I lose a few mouse buttons with the m500 but I think the truth is that I never used them all on the MX Revolution.
My advice, if you don't need wireless - stick with (or go back to) a corded mouse. I never really bought into the wireless idea; I just had to accept it to get the mouse I wanted. Now I can go back to a lovely long cable, no more flat battery delays and no more pushing a brick around the table.
The Logitech M500 was the perfect choice for me, as it closely resembles the shape of the MX Revolution. The button layout is pretty much the same, so it's like using the same mouse - except for when you lift them off the mouse pad.
(If you never lift the mouse of the pad then I appreciate that a heavy wireless mouse won't be an issue. I seem to constantly lift the mouse with almost every movement.)