Enthusiasts of slow training would be far more effective at winning over opinions if they talked more about progression and getting stronger, and less about minor details and overcomplicating training. Training is not nearly as complicated as they enjoy making it. It seems to me that most slow-speed enthusiasts are more concerned about the strength curve of the machine than the strength of the person using the machine. Regular-speed proponents like to talk about strength, poundage and progression. These factors should still be the focus if you are training slow, and are the unifying factors of all methods.
Strength is defined as the ability to produce force.
Most people fall on one side or the other when it comes to speed of motion, but I see no problem with using more than one rep speed. But you need to understand the difference between poundage and progression. Poundage comparisons only have validity when comparing the same mode of training and rep speed. It s possible to use bigger poundages but without necessarily having progressed, just as it s possible to use reduced poundages and yet still make progress. It s the same thing with speed of motion.