Oh, they will be fine I just know it... but I think in the 60's would be a tad more optimal.. plus, I only use the one heater in the large 23x26 space, so I think getting another in there, at the other end on low would do nicely.
Thanks for chiming in with your thoughts, and helping me relax a bit on the matter! I've been reading around a lot in the last hour and it seems the majority think 50's are "fine" but can definitely get some slowing of processes.
If I didn't have the other heater, I would certainly know I'm getting something good out of it, but would like to get things a bit closer to optimal... and I shall pay for it in electricity lol!!!