I thought just like you tighted 1, my arm does a great job why do I need a machine? then we got the 7424. Wow. I can polish my car in less than 1/2 hour and my arm doesn't hurt and it looks so good! When I first started using it I put the polish/wax on by hand and buffed with the PC......real dumb on my part. Its so easy to put the wax on (low speed) and buff off that you can do your entire car in about an hour, start to finish not counting the drying time for the wax. This all leads to another problem, you'll say to yourself "if it was that easy, and looks this good, wonder what another coat would look like". One evening a few weeks ago I actually put two coats of polish on. Like Michael from Orange said, get one, whatever model and you will be seriously happy and impressed. I'll probably be picking up one of the new models this fall and give the old one to my son, we share it now.
by the way Jake has one of the prettiest SRT's I've seen and he's just getting started with it, his car is beautiful.
Pat