Total Gym - a good choice

First of all a little background about me, the user. I am a 38 y.o. male who is employed in the transportation field, i.e. a commercial driver. As a teenager I was into lifting free weights, somewhere between a body builder and a circuit trainer. Due to improper lifting techniques in that day and genetics I now suffer from cartilage degeneration in the knees, lower and upper back. So I am saying that I was looking for a piece of exercise equipment to combat a sedentary life-style and not aggravate a medical condition.
I own the Total Gym Ultra. This model was made exclusively for sale through the QVC Home Shopping Network. It is apparently a grade above the model 1000. It has the T-bar, dip bars, leg pulley, and the standard pulley system. The concept is the same for all Total Gyms, a sliding bench on a variable incline that utilizes the user's body weight. The more advanced models offer more attachments thus more variety of exercises, however I have not had the opportunity to try any of the others.
I practice a bit unorthodox exercise routine. I have a very high metabolism and one school of thought says that such a person should lift once a week as they regenerate/recuperate at a slower rate. So once a week I do seventeen different exercises, three sets each, and fifteen repetitions per set. I use the maximum incline for the majority of exercises. The sheer variety and pace provides a more than ample burn of the various muscle groups.
Lying on the bench provides protection and stabilization to the back and neck. This is important to me. I shun away from exercises that would impart undue stress to my back and knees. This obviously gives me confidence and incentive to persevere with my exercising.
The motion is very fluid for most of the exercises. However this does require the user to participate, i.e. control the weight by not jerking, letting go suddenly, etc. The stretching phase of an exercise is excellent and with some exercises (e.g. chest flyes) is a bit too strong.
This machine works best for those who are interested in the aerobic and muscular definition end of the spectrum. It appears to be really effective for the chest, shoulder, and lat muscle groups. Personally I have NEVER seen better muscular definition and endurance in myself. I should add that I supplement these workouts with aerobic activities. I rotate on my off days through workouts on an air elliptical bike, air walker, rowing machine, heavy bag (boxing) and/or simple hiking.