jdub, the slow-motion type of training, which has been variously dubbed "high-intensity," "stressless," "Nautilus-style," etc., is not very highly thought of in the bodybuilding community. Of course, the "bodybuilding community" encompasses many ideas and beliefs, but what I mean is that if you talked to 10,000 college-educated weightlifters across the country, who A) have been lifting weights for at least four or five years, and B) have an IQ of 120 or above, you'd find very, very few that espouse the slow-motion system as being the best. You would find _some_ who believe in it, however, and maybe for them it really works the best.
It is interesting to try, and it is a great way to rehab after an injury. It is also a good way to work around limited equipment--you can make a small amount of weight feel much heavier. But I think that a more mainstream approach of each rep lasting a total of from 3 to 8 seconds (concentric + eccentric + any pause) is what most people find to work, and what has proven the test of time. However, I think that working each muscle group every five to seven days _is_ mainstream. I'd say that the majority of serious bodybuilders train this way.
There are many, many possible paths to success in bodybuilding, and these are not only specific to the individual, they are specific to the individual for that moment in his or her training history. What you should do, if you are in this for the long haul, is to increase your "training vocabulary" so that you understand as many parameters as possible. When you can articulate why a "slow-motion" style may be good or bad, and when you can back it up with empirical evidence from having tried it yourself, then you will have "arrived" as a thinking man's weightlifter/bodybuilder.
The lack of absolutes in bodybuilding is what many find so fascinating.
P.S.--For a shortcut approach to your question, look around your gym and see if anybody is using a slow-motion/muscles shaking/grimacing-on-the-leg-extension-machine type workout. Yes? Are they among the bigger people in the gym? Nope, thought so.