Well the shoot went well, except I appear to have a side handle where the battery won't stay in.
Used no NDs or filtration in the end as there simply wasn't time when following people about. Haven't made a clip of the welding 'proper' yet but here's one of lots of slomo sparks, and another of the 4k stuff - both exported as 1080p.
Clip 1 - Password: weldy
2k 60fps 1/120 with Zeiss ZF 50mm f1.4
Clip 2 - Password: weldy
4k 25fps 1/50 with Zeiss ZF 25mm f2.8