Button Controller 3.0 has been re-released. This offers very similar functionality to its counterpart that is built-in to Rule Machine, albeit without the more advanced aspects of RM. There are no variables, conditional actions, wait, etc. For most button device automations this app will do everything you need. Only if you need some advanced feature should you use the one that is built-in to RM (use Trigger "Button Device").
Having said that, should you change existing button controllers from RM to this app? No, there is no need to change anything you have now working in RM back to Button Controller 3.0. There may be tiny differences in app load time, but not likely to be material in the context of pushing a button. You should just leave what you have in place. One exception would that if you want to organize all of your button device automations into a single part of the Apps page, and don't need advanced RM features, then you could move them to Button Controller.