Your Bernina 150 will do an excellent job of machine quilting. What makes you want to get something else?
My introduction to Bernina machines was at the VT Quilt Festival last year. We did some FMQ on flowers and I couldn't believe the beautiful stitches it did. That was on a 440QE. After that, I used a friend's Virtuoso 153 for a wall hanging and some placemats and it did just as good of a job as the 440QE. Since then I have bought a used Bernina 180E and absolutely love it for FMQ.
Both my Janome machines give me "whiskers" on the back when doing FMQ around curves. I don't get any whiskers at all with the Bernina.
I think you already have a great machine to do FMQ with and just don't realize it! :thumbup: