If you're not using bluray to get 7ch and the lossless codecs (DTS HDMA and Dolby TrueHD), altho your streaming services may have the lossy Dolby Digital Plus, the change in audio might be more subtle than you think. I prefer to have the capabilities myself and do use bluray. Necessary isn't it so much as what you prefer/want. Using hdmi to connect your streaming/set top boxes and tv with is a good thing IMO but can you use that/do you need it? What are your future speaker and display setup thoughts? The 4520 won't work so well for 4k or Atmos features....
I don't know about "warmth" in avrs, don't think of them that way and of the four I have (two Denons, an Onkyo and a Sony) I don't think of any of them in such terms as I find them rather neutral (which is the way they should be IMO). I do like my Denon 4520, tho....is this a used, refurb or new unit you've found?