From your observations concerning hot spots with nic in 100% VG, do you feel this was from the initial mixing or separation/settling over time?
If there is a possibility of nic separation/settling in VG, could temperature could play a role? Some store their liquids in a cupboard while others use the fridge or freezer. Could this be a concern for the DIY crowd using 100mg in all VG? I have a habit of shaking anything I use but others may not.