I haven't handled one and this is more along the lines of what I was wanting to hear...mostly about the weight in the hand from a user perspective....thanks for the info.
The 4" is heavier maily because it is thicker, 0.188" compared to 0.125" with the 3". Otherwise, not much difference except for a glass-breaker on the handle for the 3," which I don't like anyway. ( I have a Scrapivore because the handle was a little longer than the Izula, but I hate the pry-bar thing on the handle.)