Many good points made in the above posts. But examining this issue differently, I'd like to share an overview painted with a very broad brush;
When the topic of surround size/capability comes up, I've posted on many occasions that modest surrounds/rears can easily produce a more than satisfying experience. I still think that's somewhat true, but everyone bring varietal expectations to the endeavor. That said, moving from reasonably robust surrounds, to highly capable, high power surrounds was a very satisfying move and one I wished I made a lot sooner.
Point being, I'd underestimated the significance of more capability in the surrounds, even in my modestly sized room. I often preach how significant dynamic capability is up front, and moved to more powerful and linear surrounds and rears to fully realize this in all channels. I just wasn't expecting the size and significance of the change.
My perspective, the takeaway here (and something I often recommend for LCR loudspeakers); dynamic linearity and the onset of compression likely occurs at much lower levels than many fully realize. It softens and somewhat veils the playback, removing some subjective realism from the experience. Most all of us readily recognize overload distortions, etc, and we back off the level accordingly. But the dynamic deviations from linearity that arise from compression (be it instantaneous magnetic compression, or simply lossy thermal effects) are insidious because they're difficult to assess until one's exposed to the effect removed.
There's more important aspects that take priority, for sure. However, I merely wanted to share how surprised I was what a welcome change was brought on from nice, powerful surrounds/rears added to the mix. I wasn't audibly over-driving my previous surrounds, and I always made it a point to stay under any audible threshold of distortion. Even at reasonable levels, the subjective change was remarkable.
Best of luck
Flat, Deep, Clean, Linear, and Loud
Active 16.8kw, 7.3 system
(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
(2)Seaton SubM-HP, (4)18" IB