V2.0:
Had LDO overheating issues
Doesn't appear to be sold now
V2.01:
Earliest version still sold?
Fixed overheating issue with a copper pour
Approx £35 as kit with 2 tips and plastic handle
V2.1S:
Has pads for MOSFETs for pumps, however these seem 'pre-vestigial' in that the functionality isn't there yet
Has a bug where there is high parasitic drain from the RTC battery (fixable by removing R10)
Approx £45 as kit with 2 tips and plastic handle
V3.1S:
Undefined 'stability improvements'
"Succinct" display, whatever that means, possibly just referring to the larger font of the temperature readout
Russian language support
Approx £55 as kit with 2 tips and plastic handle