I agree using the internal SPDT switches for this use in O scale is uncharted waters. I believe in the way we are using them we are good between 1 and 4 AMPS. I have used them to power the frog in HO scale with up to 16V track power and engines drawing 2 amps or more in some of the older QSI decoders. I have also used them to power the frog in O scale 2 rail without failure.
I also received a great email from Atlas and they pointed out that once you remove the Atlas switch machine there will be 4 posts sticking out of the sleepers. Those post are wired to the rail so you can just solder to those instead of drilling through the track. I am going to post an update video once I get more input from other members.