Ron Ketcham said:
For trucks, buses, boats, use the one's with "flayed" bristles. They don't mar near as much...
The flagged/flayed/split bristle tips are crucial! When they wear down (as with my BHMA brush) then the marring begins. Gotta CD-test regularly to catch it before it becomes a problem.
Use one on a nice car, don't think so...
I use 'em for the initial passes on all my vehicles, to "get the big stuff off", safely. Absolutely zero marring. NONE. Not in any lighting and I do use magnification. Well, not any marring from the brush in-and-of itself...sooner or later some little bit of dirt...well, you know- "marring happens".
The only downside is that when the right BHB (i.e., one that's soft enough for me) is used properly (constant lubrication and flushing from the foamgun), it's *SO* gentle that it barely even gets contamination off. Gotta do several passes with it and then follow up with a mitt (using increased contact pressure).
Short of using a pressure washer (which I can't feasibly do for various reasons), a good BHB is, IME/IMO, the safest thing going. And I can assure everyone that I'm as fanatical about wash-induced marring as one can get
...but they do have their uses...
Ones that I wouldn't use on my hood work OK for wheel wells, undercarriages, calipers, and some wheels (more delicate wheels get BHBs that're just as gentle as my "good ones", which are a huge PIA to use because they're so gentle and the wheels get so nasty).
Ones that *might* be OK for regular use (but are borderline) are handy for tight spots in doorjambs. Safer than a swab because swabs tend to press dirt against the paint a bit too firmly.
..Next to impossible these days to get a boar's bristle without a 2nd mortgage on the homestead...
Eh, they're not all *that* pricey, but I guess that's subjective. Not having to polish out wash-induced marring for many years at a stretch is priceless to Yours Truly

Seems like the prices have't gone up all that much since the '80s...back then I thought they were awfully expensive.