Brian,
My 4900 performed very well for the first ~14 months, then developed serious problems that were going to cost more to fix than I paid for the printer. I decided to cut my losses.
I was dissapointed that Epson would not help, all they would do was refer me to repair shops in my area. But since I did not buy the extended warranty, there was no legal obligation on thier part.
While the printer worked, I was a very satisfied owner. It produced excellent output and gave me very little greif.
Do 5% of 4900s experience serious problems, or is it 50%? Someone at Epson probably knows, but the're not talking. Hell hath no fury like the owner of a dead 4900, and they tend to vent on the forums. Meanwhile, satisfied owners just go on printing. There is simply no way for us consumers to know what the failure profile looks like, or why Epson has not acknowledged problems (maybe it is only 5%).
If the 4900 meets your needs better than other models, go for it. Be aware that there is a chance you will need expensive repairs at some point, and if that causes you to lose sleep, consider the extended warranty.
Hope this helps, but I'm guessing it won't...
Dave