If you want a program that has zero preparation work on your part (but can still be customized, as necessary, to meet the needs of all of your children) and is very quick and painless, definitely go with AVKO. In our experience, it's not about efficacy per se that really separates out the various Orton-Gillingham-based programs -- all of the O-G methods are effective, especially for dyslexics. What does separate out the programs is the ease for the parents to teach it, and the students' levels of frustration. When the complicated rules for spelling are taught, it becomes more of a hassle most of the time. The rules are very abstract, have multiple exceptions, and are not easy to remember. But, most importantly, when rules are taught, and the child tries to apply what he has learned and gets to an exception, he gets even more frustrated than if he had misspelled it after never having studied a supposed-rule to begin with.
In some languages, it makes sense to teach rules. In English, it makes sense to teach patterns. Being an amalgamation of so many different languages and retaining so much of their original phonics, it becomes very difficult to teach rules that cut across the entire spectrum. So, we don't.
However, we do have materials available on teaching the spelling patterns that are common (and uncommonly taught) in English. I would recommend that you see our page on Sequential Spelling (ss.avko.org) -- on there, there is a link to how to customize your Sequential Spelling program. This will be of great interest to you, I'm sure. http://avko.org/Essays/