I am currently using a $40 Hamilton Beach. Obviously a Jack is higher in quality, but does it give better juice? Do the higher RPM machines do a better job, or do they create more heat, which takes away from long term storage? I also have a manual wheatgrass juicer which is great for several ounces, but making a quart of Celery or beet juice turns out to be a chore. What is yor opinion on this?