Wow, I learned a lot about calligraphy history in this thread !
I recently read a book by the french calligraphy "master" Claude Mediavilla, it covers all the traditional calligraphic hands and even has a chapter on gestural calligraphy... In the chapter about copperplate, there is just one small paragraph about spencerian (it is not named though) where the author just says that this "evolution of copperplate carried the seeds of its decadence within itself"... I was appalled!!! I still love the copperplate exemplar in the book, though.
I started learning spencerian in september and my love for this hand only grows with time. At first I found it very "mechanical", but as I started to study the masters specimens, my love for it grew more and more. It is definitely not a very familiar hand for us europeans (Some capitals are just not legible for us), but all I can say is that I cannot understand how one can find it "decadent"!
Both hands are absolutely gorgeous in my opinion, but there is something more subtle about spencerian that I find fascinating. I also heard Paul Antonio say that once you learn spencerian, it changes the way you write any other hand because of the muscular movement... That is very true, my hand does not move in the same way as before, I love it changed me!