I work under vehicles daily. my own set up is an edc18650/convoy s3 lanyarded to my work trousers with a bayou clip as back up. an oem d4/convoy m1 in a holster for general work. both of these use 4c emitters for now. The edc uses an ld25 driver, the d4 uses a reylight blf a8 driver. I also use my oem d5 with qlite and 5a1? xm-l2 and an a8 clone with the same emitter/driver. All the 18650 lights will happily sit in a niteize headband which is how I tend to use them. I found 4c is good as the more neutral tint reduces glare from components. However, the 80cri xm-l2 is a million miles better for this reason, then consider your friend may be working with wiring looms, that is where the higher cri really comes into its own.
The a8 clone is used for flood and longer jobs as it is a 26650 tube that tail stands nicely very very useful.
Also remember, though the qlite can deliver 3a on high, you do have modes, I rarely if ever use high on a job, but its useful to have it available.
I’ve used cheap zoomies and c8’s, the c8 if properly specced is a very very good headlight for long drawn out jobs as it handles the heat better, the zoomies were absolute crap, like they are in any other application - crap tint, never give the “right” kind of light and generally give tint shift in you peripheral vision, its extremely distracting. they are also either pathetically underdriven or cook their emitters.
no, zoomies are not the way forward.
An op c8 with qlite/80cri xm-l2 would be my upper limit in size and my preferred size is 20 –30 mm reflector with a decent amount of mass, depending on the exact job, he may need high more than you think, he may never need it at all.
The other thing with the qlites and ld25 is the pwm is almost undetectable, that’s important around moving machinery as again, you tend to pick it up in your peripheral vision and it can be bothersome.
I wouldn’t worry too much about ha2 vs ha3, its going to get banged up whatever coating it has, fmc’s magnet conversion is also well worth looking into, very very handy mod.