The v4 rotors are wider (I think they are three layers of laminated metal 2 steel with aluminum core). They will only fit on the V4.
My hope brakes aren't sharp to the touch but they feel "machined" in that the edges have a more prominent feel. I would say the lever is not as ergo as many others but it is fine and nice to look at. The lack of fade is of note on my E4's as well. I rode those for 2 years in Nelson where the downhills can be an hour of nonstop descending on steeps and never had fade be an issue.
