My 'big' machine is a Janome 6600 and I love it, love it, love it.
I just recently also bought a Janome 3160QDC to be my portable machine and it's a dreamy little machine. It stitches great, LOVE the scissor cut button, and as Sally J described it, it really does just 'purr'. My dealer has them out for test-drives, you might be able to find one to test out.
The only thing I want that it lacks (that my 6600 has) is I can't seem to program a default needle position, so I have to keep a sticky note on it to remind me to adjust the needle for a 1/4-inch seam each time I turn it on. WOE IS ME, right? LOL