Well, I just learned a valuable lesson a few days ago. If anybody is using a custom 901 connector that utilizes a soldered center rod, be careful.
What I noticed with the KR8 cartomizer was that the connector has a slightly depressed groove in the center. This can catch the center rod on a custom battery connector, and acting as a sort of screwdriver, twist the rod and undo the soldering. I think this is particularly applicable if the center rod has a slight notch (for air flow).
I don't think many custom 901 connectors like mine are floating around out there, but I wanted to just make the issue public. If you have an original Zi Moshi LiteVaper (made by Ted), then this will probably apply to you.
Regards,
Brad