for me frame quilting was so much easier but i had already been FMQ on a DSM for a year before i got the frame.
the hardest part for me was dealing with the throat space on a frame because you can't puddle a quilt like you can on a DSM.
when i got my frame i only had a 9 inch throat and doing a 12 inch design took a lot of stopping and rolling of the quilt vs. on a DSM i would just puddle the quilt and do a 12 inch design without stopping.
i have an 18 inch throat on my frame now and i still use my DSM for FMQ too. i only put the large quilts on the frame. if i'm doing a table runner or a small wall hanging i'll just FMQ on my DSM.