I agree on the following:
- Upgrading power poles (this has been requested before). If they should be downgradable like conveyor belts, it should only be possible, if the downgraded version can support the amount of current connections.
- Rotating machines 180 degrees, if they are not connected to a conveyor belt (as long as they don't add machines, that are not symmetrical)
I disagree on:
- Swapping of splitters and mergers. If they are connected to belts, it will cause problems. If they are not connected, you can just deconstruct and replace.
- Make belts reversable. If you could do that, connected machines would have to be rotated aswell and I can think of a lot of problems with that.
I think, if you have a conveyor going in one direction and try to connect anoter conveyor in the wrong direction, that it should flip in the correct direction, as long as it is not connected to a machine.
edit: I think rotating machines could cause problems, if the maximum wire distance will be exceeded after the rotation.