I quilted on my domestic machine before I got my midarm. My preference is definitely the midarm -- much faster for me, plus much easier for me to move the machine instead of the quilt.
You can quilt large quilts on a domestic machine by splitting up the batting. Basically you layer the sandwich as usual, but then remove one-third of the batting from each side so there is less bulk under the arm. Marti Mitchell has an entire book out on different methods for quilting large quilts on domestic sewing machines. (Be sure to get more details on how to do the method I described before tackling it; there are a few steps to doing it so that the batting goes back together accurately.)
A lot depends on finances. Beginning frame setups for quilting start around $2,000. This can be a good investment for someone who would otherwise be sending out a lot of quilts to a longarmer.