That's possible. I'm dealing with babies so a more mature plant can handle the cooler temps. I saw your results so I'm not going to dispute anything!
And now I won't stress out if my water temps drop a bit once they grow up a bit more.
In my current situation, my plants weren't thriving, droopy, yellow, etc. even after fixing everything else! I changed water temps and they became much healthier. As long as this trend continues why change?
I guess it comes down to just watching your plants and let them "tell" you what they need. Let's say, even if they are in 40* water (highly exaggerated) with big healthy green leaves and just a bit of slow growth, why change what's working?