Hi Servando,
unfortunately, like you, mixing is still something I struggle with and try my best to avoid at all costs (along with mastering). I also bought the Bob Katz book some time ago along with a plethora of other books in an effort to improve my mixing and engineering skills. I spent several years producing mixes that were OK but not really what I had wanted. I also find that the longer I spent on the mixing and post-production work, the more I lose interest in the musical aspects of anything I am doing - it feels too much like work for me (if that makes sense?).
For this reason, MIR for me is such a fantastic product in that it allows the realisation of a first mix without much of the complexity normally associated with this process. I fully accept that there is still much that needs to be done from this starting point however just getting to this first stage is a huge leap forward which then allows the fine tuning to be done (or not! depending upon the goals of the individual and the purpose of the mix).
I'm probably not qualified to do anything else other than enthuse about what MIR brings to this whole creative process at this point in time but I would say that you aren't very far off with what you are doing so far. I'd be interested in how William acheives some of the fantastic depth, warmth and expressiveness in his mixes as this was one of the things that blew me away. Not only the music but also the finished product was superb which I know isn't something that is easy to acheive.
Tom