I have a friend who is in charge of a sports team at our local College. He has a large budget and could purchase any sort of machine that he wants. He purchases "Hammer Strength" exclusively for his athletes.
I see no problem with you using this product. I have used a variety of free weights, machines and other "gizmos" through the years.
Remeber one thing: If you are going to train for life you are going to need variety in your training! Sure Barbell Squats are better than using a Leg Press machine. However, After so much time training with Barbell Squats the Leg Press machine looks mighty good. It can renew your interest in training to have some variety over the long haul.
Ask some of the greats that have been in this "business" for longer than you have been alive: Dave Draper, Arnold, Franco, Lou Ferrigno, Reg Park etc. These guys are bigger and more successful than anyone on this board! All of them have used (and continue to use to the best of my knowledge) machines.
I have some Atlantis pieces in my home Gym and use them all the time.
A good example of my use is after finishing up four sets of the Cleans. I move directly to my bicep machine and knock off two fast sets. No muss no fuss!
Another good way to use machines: Sometimes when you are just a bit fatigued and are going for a few final additional sets a machine is exactly the right answer. There is less of a chance of injury due to the "track" the machine follows.
There are limitless ways to train with machines, no different than free weights in that regard.
Basically, I am a free weight guy, but I never say never when it comes to a really good piece of equipment. No thinking man does!