I have a 6600 and I agree that in some circumstances the lighting is not adequate. It's weird because I have a desktop Ottlite and sometimes it helps me see better, but sometimes I see better without it. I think when I work with very dark colors it helps to use the Ottlite. I'd say it would be a good idea to get an Ottlite and then you have it when you need it. I agree with Jean that they are a tremendous help when you have to rip out stitches.
The one draw back with my Ottlite is that it gives off a lot of heat. I don't mind that in the winter, but it's a little much sometimes in the summer.