Craftsman 109's are actually produced by Dunlap, not Atlas. Dunlap sold the same model as well, but they mainly made them for Craftsman. The Atlas 618 would be a huge upgrade to the 109, in weight, rigidity, normal backgear, and a larger spindle (Planetary on the 109, a weaker and more fragile back gear setup then the 618, but it is more compact). I used this lathe before the SB came along, it did everything I needed and for $75 I can't complain. I know that thing in and out, washed every part by hand in the basement with Kerosene ans reassembled, the right way. Most screws and parts got antiseize, lithium grease, black grease, or light oil depending on the application. Or at least I THINK I did it the right way
Time will tell.
Since the 13" was wayyyy to big for the basement, I keep the 109 in the basement for winter jobs. It's quieter than a mouse, can hardly hear it 15' away and can't at 30'. With a 1/4HP Emerson electric motor it made a perfect combo.
The real downside is the small spindle, the chuck will bow away on mild cuts in steel, but a spring cut or two and a little strip of 400 grit sandpaper you can get small parts to tenths, if your careful!
The 109 is a good lathe, if you can work within it's limitations.
Oh, and the pics above were taken with a jewelers loupe in front of the phone, a great trick for adding a little detail with lower res phone cameras.