I've been following this post for a while and am left thoroughly confused as to why so much effort is being expended trying to figure out which saws to buy and how exactly to outfit them before you've even figured out what your needs are based on on-the-job experience. Theoretical versus actual needs are often much different, after all. Plus, having a large collection of saws sitting around doesn't make you any money.
Why not buy a couple saws, see how they're meeting (or not meeting) your needs, and then adjust. Coughing up for a large initial investment in saws you might not end up using seems wasteful. Or how about this: go buy your 440/460 with a 20" and 28" bar, run the 55/455s into the ground, and then after the Huskys crap out get a couple 361s or whatever your needs then dictate? That seems like money better spent, in my opinion, because that way you won't be buying saws you don't need.
I had in contemplation to do something along the lines of your plans - have saws at each displacement level - the perfect tool for each task. I am glad I didn't go out and do that, because I found that I can do 80% of my cutting with my 80cc Domar and the other 20% with an Echo top handle. Most of the other saws I've had have either been retired, given away, or sold. I keep trying to convince myself that I could use a 50cc saw, too, but have yet to see a true need for it. As a result, I have fewer saws to maintain, fewer different bars/chains/spare parts to keep around, and a bit more money left in my pocket. And it feels good.
Obviously you are free to buy whatever you want, but I have found that experience is generally the best gauge of what is necessary to accomplish a particular task. See how far you can go with the stuff you've got now and a minimal additional investment and then adjust accordingly.