>the 8 char password has much less entropy: 95^8 ~= 6.63E15 //
Most of the word usage is going to be limited though too. testyourvocab.com put the average at 27k I think. We're looking for words one can remember easily so the word pool is going to be a lot lower - 15000^4 ~= 5E16 FWIW.
I love the backtick in my passwords. If a website accepts it and doesn't give me any issues, it's a decent indicator of basic security.