My main point of failure has been from the coil and nail being too tight of a fit.
Someone said that it should feel like pushing a plunger into a syringe when you're inserting your banger into the coil and that sounds right. Very minimal resistance and it should push in gently. Firm and snug but not tight.
I always fit my coils when everything is room temp. I don't turn everything on until the clip is installed and I think I'm good.
Hearing the coil creak while it's on is usually not a good sign. If it's creaking I usually assume it's gonna break while cooling down, and I'll either very gradually drop the heat and cross my fingers... or I just leave the enail on
I've only used the fat bottom bangers but just got some opaque ones that are on the way. I'll report back later this week on how those fare.
I personally found better taste from lowtemps on the quartz bangers than on my small SiC dish from the wraparound flowerpot, but I am also gonna test how the new, bigger, SiC dish fares this week as well.
For reference I have only used bangers from dhgate, quartzbangers.com and fatdabco.com so far.
cheers and have fun