My thought process is the metal lines will conduct heat a little better than rubber can. You don't want to overheat your oil, and the slower flow rate to a bypass filter will make it more likely.
The percentage of oil that would even have the potential to get overheated….is quite small relative to the volume of the pan. Bypass system, we are talking about.
Whatever minimal heating happens in the line (in theory) would be immediately diluted when it dumps back in the pan.
