That's an impossible choice. A threadle 411 is very attractive, the job is to find the perspn who knows and cares about this kind of thing. The machine I use the most is my 201K, a flat bed in a small table makes it even more hand with some types of jobs. It's a favorite and I haven't found any nicer machine to work on. I have to have a freearm model, two machines are a minium. I would keep these two regarless, and my 99K. I don't know how you think about it. Is you Sphix a 27 or 15? I think they both should turn fine for many types of jobs. If there's a machine I never use I would easily let someone else have it. For gems like this, make sure they go to a good home.