I've always seen positive posts about the Janome Jem (all versions). If you're not satisfied with the mini, I would definitely return it and get one of the Jems instead.
The "Hello Kitty" is good too if you want a really simple machine and don't mind the color. (Someone said they will eventually be collectible, but I don't really know about that......)
If you do a search on Amazon for Janome Jem, you will see some of the different versions of it. I would think for piecing the Gold would be more than enough.