I understand this, fully. I shoot the larger G5...and I experience the same issues you do. To ME....going to a smaller peep isn't going to help you. I center my sight housing inside my peep....and it creates a "halo" effect inside my peep when I am at full draw (I can see a "halo" of daylight around the outer rim of my sight pin guard.....inside my peep). In low light conditions.....it becomes harder to discern the "halo". You can be somewhat centered inside the peep.....but be off a little and not be able to tell. That would attribute to the inconsistencies in accuracy.

I understand fully what you are describing. I have issues indoors, as well. I've tried more overhead lighting (basement).....back lighting.....to no avail. I can't recreate "natural" lighting that we get outdoors.

IMO....it's simply a product of our method. You COULD go to a smaller peep.....and center your sight pin inside it. I became much more proficient/accurate when I went away from this method to the one we share, now.

I'd ask....do you get the "halo" effect? It woud depend (not on the size of your peep, necessarily.....but how your peep AND sight housing work together) on your equipment.

Good luck.