Ya man, think about it, you'll still get internet and data back and forth from the router when needed however when doing lots of file xfers, why not go a more direct route with out any router processing. USE your switch man. You'll see a difference between those wired devices.
Up to you man, The 4500 is a great router and so is the 825. The 4500 no longer being developed on. Really, doesn't need anything else. LOL, if your ok with just using 2.4Ghz and don't have a need for 5ghz and IPv6, then 4500 is good. The 825 is a bit more flexible as it can do both radios at the same time and does have support for IPv6.