If your plants look great, then I wouldn't change anything in your current grow. The rest of this post is just FYI, food for thought on your future grows.
I'm currently using 10-gallon Smart Pots as well in an organic grow. My temps are higher than yours (65 lights off, 78 lights on), but my humidity is similar to yours.
My current soil is an organic soil I mixed myself. And it's very airy and drains well (due to lots of added organic rice hulls). When I first put my plants in this mix in 10-gallon smart pots, I was watering every 4 days. Now that my plants are well into flowering, I'm having to water every 3 days.
I've used ProMix BX before (and I added extra perlite), and as I remember, it retained water a lot more than my current mix. I didn't have to water as often with it.
Personally, I much prefer the "quicker" wet-dry cycle I have with my current mix. In fact, it's pretty much impossible to over-water my plants in this mix. That lets me know the roots are getting plenty of oxygen, and I don't mind watering a bit more often.
Good luck.