I have a Janome DC2007, which is the equivalent of the DC2010. I love mine so much. It's an excellent machine with not a lot of bells and whistles, but enough to get the job done. I've said it a million times, but I'll say again that it's never given me a day of heartache that I didn't cause. It's solidly constructed too, which is rare for a not super high end machine.
On the refurbished question--I would only do this if you were buying from a reputable Janome dealer. The nice thing about buying from a dealer is that they can sit down with you and the machine and give you a feel for the machine and answer any questions that you have. Janome is big on education too, so your Janome dealer should have classes that will help you with your machine. I'm not too sure about the 115215. It's not listed on Janome's website which makes me a bit suspicious of it's origin. There are some big box stores that sell cheapy Janomes that are made in China that are not the solidly built good quality machines that you want.
I hate to sound like a commercial for Janome, but you'll be really happy with a 2010.