Thank you, gramfel and midwifehc.
I've also seen some reviews of the Bernette commenting on the tension issues.
This particular model came out in December; I haven't seen a bad review, but haven't really seen much at all. I know one quilter whose mother bought it and is very happy, but would like to have more than one opinion. Somebody must be buying them - when I did a search on the model, several stores that sell them had comments that they can't keep them in stock.
Here's a link to the model I'm considering:
http://www.berninausablog.com/read/retro-bernette-46