New Ender 3 V3, Why .STL's?, Printer Safety and MORE

This Episodes Questions:

 I want to make this printer as safe as possible but it will require a lot of power.  AC powered heat beds are getting more and more common but every video I watch on the topic makes a point to talk about SSRs failing with the power on (closed circuit?) even when talking about high quality and over-spec SSRs.  A thermal fuse will prevent a melted bed but then I still have a potentially dangerous situation with 120v AC power.  I am very well aware of the recent A1 recall and don't want to turn this into a bambu discussion.  I think we can all agree they shouldn't have put an AC powered heater on a bed slinger and call it a day 
Peter
 
 .STL files are ubiquitous, but are there better alternatives such as .3MF? What are the pros and cons of different file formats?
Also, do you have any recommendations for export settings when exporting a 3D file from a CAD program.
Thanks!
Austin

Hi Guys,
I enjoy listening to your show here in the UK in my workshop. 3D printing started as a much loved hobby and has now turned into a big part of my small business 3d printing light fittings.
Anyway, I'm currently running a bunch of Ultimaker 2's and looking to to upgrade.
I print pretty much everything with 1mm - 1.5mm walls and a 0.5mm layer height, lots of spiralize/vase mode. Id love to hear your opinions on which printers can print wide walls and big layer heights with good cooling to speed my production up. I found that the matchless nozzles from 3D solex helped btw. Its definitely time to ditch the old UM2's though (I'm not considering Ultimakers, they're now hugely overpriced IMHO). I'm not after huge build volume either. Bamboo is a no for me due to IP worries.
Thanks and keep up the good work!
Jamie Norris Green - Leeds - UK