Speaker size and room interaction

I recently got a Rel T5i and it sounds fantastic.  I just plopped it down, hooked it up and bam, great integration with a more solid foundation for the music.  It sounds really great.  I bought it with the intention of getting 1-3 more.  
Anyhow, I have also had a Rel T9i and Rel Sho S3 in this same room with results that weren't as good.  The S3 was the worst actually.  Over powering, hard if not impossible to integrate, directional bass, bigger peaks and nulls, etc....

I’ve wondered for a long time now if we should be placing more emphasis sizing our speakers to our room appropriately.  I look at the speaker / room interaction in much the same way as driver / cabinet interaction in terms of pressurization.  
Anyways, I thought that I’d share my experience with the T5i actually sounding better than the T9i and Ss Sho in my particular room.  I can’t wait to get one more, then 2 more eventually for a swarm setup