probably the most apparent reason for machine quilting over hand quilting is TIME- it takes a long time to hand quilt a large quilt which you can machine quilt in a few hours- so, if you tend to stack up tops waiting and waiting to finally be quilted- you might want to machine quilt them- but some people decide they really do not like the process---so you really should visit some quilt shows & dealers & try out a few long-arms to see if it's something you think you will enjoy. if you enjoy hand quilting then no reason to stop- you can of course continue to do both after having a machine- but a long arm is a large investment- so you don't want to invest then find out you really hate doing it- you have to keep in mind it means standing for long periods- working your arms, shoulders, hands- strain on the back, legs, knees-
i allow people to take a class to learn to use my machine then rent time on it to quilt their quilts---99% of those who have done that decided after one or two quilts they would really rather pay me to quilt for them- they just didn't find it all (their cup of tea)