I think “too far” is a matter of how you feel about your cat.
We had an outside cat and my wife bought a heater for the cat bed. I put on a Z-Wave on/off module that turned on when it was below a certain temp. We didn’t bother to worry if the cat was actually in the bed.
At 11W 25% of the time, it’s like 2.75W all the time. I wish half the other gadgets I’ve got plugged in were that frugal.
I used X10 in my apartment in 1986. I wasn’t aware you could even buy any of that stuff anymore. X10 sent data at the 0V crossover point of AC power and this made it slow and suseptible to noise, and therefore also unreliable.
I’d avoid, TBH. There are so many better alternatives at this point.