I understand that older eeros and current ones can all work together. My question is if I get a new eero pro router, but continue to use my other 2 original eero extenders, will that be better or faster than just staying with all original eero bundle? I just don't know if my new eero pro 6 will be held back by the original 2 extenders that came with my original eero. Or to improve, I must get the new eero pro 6 AND the other 2 that come with it?  Thx