I read in the thread that High Gain is used only when the source is weak and I suspect it will drain the battery quicker.
Last nite, I was out and about with the Intruder and it suddenly got no sound coming out. I quickly went home and fanatically testing with SE/balance input/ouput different cables/iem...... because the red light was still on... all of a sudden, I thought I should charge it full again to test... and it turned out that the battery was low LoL
If The Lightning is not too expensive, it may not be a bad idea to get it also as a backup..