I saved up and bought a Janome MC4900QC.
I was in the same position as you - had straight and zig zag and wanted more...
Now that I have had the machine for about a year and a half I wish that I would have gone down to one of the lesser ones... I NEVER use the fancy stitches at all. shhh! don't tell my husband! I have actually tried to sell it on craigslist but had no takers. I would have liked to downsize.
I will say that had I not gotten it I would never have tried a walking foot or a 1/4" quilting foot both of which are always at hand these days!!