Well, here she is! She arrived yesterday but I was on my way out so this is the first chance I've had to have a play.
The differential feed means that you can tackle a range of fabrics and achieve a good finish. I have always struggled with stretch fabrics, and the Janome (she doesn't have a name yet) seems to be just the job.
I made lots of samples and noted the settings on them for comparison.
Although I tied these on the existing threads, I get myself in a muddle changing from 3 to 4 needles so I did actually get a bit of practice threading from scratch. This Janome has an easy feed mechanism which is ... erm ... easy to feed.