Reason for the driver was that there was some confusion. Our ThorFire contact is not technical - the engineer responsible (poor in English) said our driver was not production ready - we don't know what he meant, and he no longer works there, so we never found out why he thought that. Since the parts were changed (different MCU, different FET), I was speculating it was costs/availability. The process for the driver has been re-started with a new engineering team so hoping we hear back soon with details. The MCU they used was unmarked and didn't match an ATMEL AVR or a PIC I know of - the ground and VCC pins were not the same as any MCU I'm familiar with.
Double springs have less voltage drop than single. The Fenix PD40 is an example of a high quality, high output light using double springs on both ends, and advertise it as such here: http://www.fenixlight.com/ProductMore.aspx?id=1155&tid=9&cid=1# in this picture:
Usually a bypass will still be better though, but we thought, as others have, offering the light shipped with double springs will be an advantage for those without the skills or time/effort to solder in 4 bypass's, same as decided for the BLF X5/X6 and Cometa, etc.
Also taken from a Ronin42 post in the X5/X6 group buy thread:
here is a quote from the Manker T01 review:
“ Inside the tail cap we can see something I’ve not seen done before in a light – dual cathode springs on the cathode PCB. The main spring is super thick for optimum electrical conduction. A second, thinner spring rides just inside it for increased flow of electricity. Think of it as having a factory spring mod. Both appear to be gold plated.”
So, not sure, but maybe Manker originated this, or Fenix?