Just have the magnetic puck exactly in the location where you leave your controller when not playing and done, never think about the battery and don't swap things.
I, for one, still don't understand why you want to swap batteries. I'm assuming you're talking about rechargable AA batteries, and not the environmental disaster that are single use batteries. How's taking the batteries out, going to the charging station, swapping the batteries, returning and installing them back into the controller less convenient that just dropping the controller onto the recharging puck when it's not in use?
So you have some special conditions where you can't recharge the controller between sessions?
Dave2D mentioned that Valve said it isn't aiming to directly complete with consoles, but rather sff PCs. So the price will likely be in the $700-900 range(?)
I live in small apartments and I would know if my cat got on the table or counter, in the very least by the jumping off thump. In fact, it was happening in one particular apartment. IDK why, but he would get on that counter. And yes, usually during the night when nobody is there. Doesn't happen in the current apartment.
Dark Matter (2015) is doing most of the heavy-lifting.