galvanized vs. poly well pipe?

I am about to have replaced a deep well submersible 2 HP pump. I don't know the exact depth, but given HP rating, probably 300 feet plus. Current pipe is probably galavanized. Since they have to pull it anyway, I am going to replace the pipe.
What are the pros and cons of galvanized vs poly? I don't mind the cost differential, all the $$ is going to be in the labor etc, and I want to do it the best/right way.
Anything else I should have them do as well? (besides replacing check valves). Should they replace the electrical line?

One other thing: I did have some pinholing in my 30 year old copper feeder pipes in the house. I assume this was from minerals and hardness/low ph (raw water is ph 6 and 4.2 hardness). (the problem was on the feeder lines before the water treatment system). Will galvanized react the same way? In other words, if I had this problem with copper, should that be an argument for poly?

 

Use the 160 or 200 psi poly. no joints, no corrosion, and you can possibly pull it by hand