I bought my Sweet 16 last August and I love it! It has no feed dogs but stitch in the ditch can be easily done. Almost any tool that can be used on the stand up machines you can use on the sit down versions. It is extremely easy to use if you have ANY free motion experience, even my 5 year old granddaughter had fun on it.
For or the uninitiated--a Sweet 16 is the same machine head as the stand up versions and can easily be put on a long arm frame. This was a great selling point for me.