This is a pretty good post. The weak part of it to me is that I have never felt pushed to use any particular new fancy type stuff if I don't want to. Don't want servant's type-level http apis? Drop down a level and use warp. Libraries are often layered this way because it's understood that excessively complicated types can be a trap. One does have to develop an intuition for how far to go, which will involve making mistakes.
Do you know of a good "I don't know Haskell well but this Servant idea sounds incredible, please educate me?" article? I read the Servant docs and they (rightfully) assume I have more Haskell understanding than I do :(
