Couple thoughts... make certain your avr or amp is stable to 4-ohms. I just helped a friend looking to power his 603s, which have a dip to 3.1 ohms. Yours might do the same. (Just a thought.)
You really only need to match your front three for best sound in HT. If you are going to do 5.1 audio, maybe you want your surrounds to match your front three as close as possible (how I built my rig) but beyond that outlier preference, surrounds, rears, and Atmos don’t need to match up as seamlessly. My preference is do it if you can, but if you are on a budget, or are worried about sensitivity or having something easier to drive... it’s not a problem to change brand.