Same experience as I had with mine. I began seeing the graphics artifacts around mid/late October, and held off doing the RMA because I had so many new games I was wanting to play. I finally filled out the form online in November to return my Wii, and still didn't send it off after I got my hands on SMG. Finally, when early December rolled around I got a PS3, so I figured that was the time to ship off the Wii while I had a new diversion for a week.
I think it was only two or three days from my filling out the RMA request on the MyNintendo Web site to receiving the UPS shipping label, and it wound up being about 9 or 10 days total before my replacement Wii arrived. The return slip that accompanies the new Wii covers your SN in and the new SN out, so that you have a proper paper trail proving ownership of the new unit, but in my case Nintendo did not transfer anything other than my MyNintendo account link. They did not copy any of my save data or any of my Miis. I did have all my saves on a Memory card, but I had forgotten to copy my Miis over to a Wiimote (not that it matters, because they wouldn't be editable anymore on the new Wii).
Nintendo's CS is awesome, however I don't think their R&D team does them any favors. It's not NoA's CS teams' fault, but having to distribute a new friend code and recreate new Miis because they can't be backed up to SD cards or edited on new consoles -- really just having to go through all of that again is a HUGE problem in the core design of a systems' avatar functionality. I'm very disappointed with Nintendo in that respect ... nearly a years worth of FC exchanges, Mii-trades, and Wii Sports records and points: Gone.
