Speaker and AVR impedence correlation

I just bought the Emotiva T1+ tower speakers, and am looking to find an AVR to pair with it. These are 4 ohm speakers, and doing some brief googling, I read that I should find an AVR with 4 ohm minimum impedence as well. AFter doing some digging on the sub though, I'm seeing a lot of comments saying 6/8 ohm avrs will run fine with a 4 ohm speaker https://mobdro.onl/  

. Can someone clear this up for me? What is the pro/cons of getting a 4 ohm avr as opposed to a 6/8

I got this,..