I would be very, very suspicious of claims about this. Grading patterns and fitting them to a specific person is much harder than simply plugging numbers in to a program. You're likely going to need to do significant fitting of the pattern. (Also, without getting too deep into the process, you're going to need to either have a very wide format printer, or a pen plotter, in order to use the patterns. Which certainly isn't the end of the world, but most people don't have a 72" wide roll-to-roll printer at home.)
I'm saying this as someone that did their undergrad work in fashion design, and used to be pretty decent at pattern making before I switched industries.
I've used multiple flat patterning techniques from a range of authors; you can get some really weird results when you plug your own measurements in, versus the 'ideal' measurements. For instance, I always need to significantly pitch the back of jeans patterns for myself (like, 2-3" or more); some ways of creating a jeans sloper end up being so incorrect on me that they don't work at all.