Lovely work, lovely colors! Regarding the 6600 P, you won't be disappointed. My neighbor recently bought one and she loves it! She's been busy making purses, so hasn't done any quilting on it yet, but she will get to it in time.
Piney, I also have a Janome Jem (Platinum 760) and have fought with small projects so I know what you mean! My larger machine is a Kenmore zigzag (can never remember the model) from the 1970's. I haven't tried doing any quilting on that, but it does have a bigger throat than the Janome.