Brand name on keyboards means little to nothing, just get a cheap keyboard and you will be fine.
As for the G5 and the copperhead... I would say it comes down to this.
The G5 is an awesome mouse, but it's middle click is very stiff. It can be somewhat annoying sometimes since you have to press it so hard you sometimes accidentally scroll as well. Other than that it is a great mouse.
The copperhead has side buttons in locations where I accidentally press them frequently. This causes the cursor to speed up to the point where it is difficult to use until I click the back button on the side. This is probably equally annoying to the stiff scrollwheel button.
Depending on which of those annoyances annoys you more, pick the other one.
They are both great mouses, and it really is nit picking between them.