lol,
well, V4 is over now, I mean, I might keep a few PCBs as spare parts or for personnal projects during the V5 design, but so far, since v1, many bugs and hardware details have been fixed, upgraded, improved. Honnestly, V4 is REALLY stable. My only current problem is the microcontroller, I can't figure out when I'm soldering them but *some* of them have a fragile on/off or aux button input. It's fine during the test then some people will end with a board that isn't responding to the on/off control, after soldering the switch.
Excess of ESD is a possibility and... awful soldering guns. Think about investing in a 50 USD smd soldering station, and please NEVER use any sort of soldering so-called "gun" (pistol shape).
Erv'