Different people, looking at different paints, have different preferences when it comes to what light to use. People can even differ regarding what time of day/angle of illumination is best with natural sunlight. Or whether sunlight is all that demanding compared to other choices. What about at night under high-up-there parking lot/gas station lights? What if you keep working at inspecting that "perfect paint" for another half-hour or more, changing up all the variables? Heh heh, how much do you really care?
IME, SunGuns work best for very fine holograms. It's the only way I can *ever* spot them other than in natural sunlight, and Mike Philips has teased me (good-naturedly) about using the SunGun because under some conditions it's *less* forgiving than sunlight. It has its uses spotting other types of marring too, but those types can, IME, be spotted under other, less pricey, lights. Unless you're using a rotary or correcting somebody else's rotary work, I can't imagine somebody actually needing a SunGun and their batteries are simply awful.
Can you spot *all* the marring that *you* want/need to see so that you never have any "oops, I missed that and it matters to me..."-type discoveries? If so, then just keep doing what you're doing. If not, my best advice is to just experiment until you find out what works best for *you*. Remember to vary the illumination/viewing angles/distances too; this can take a while and I don't mean just an hour or two with one or three different versions of each variable. It's one of those things where I don't think others can answer the question for you.
OK, just FWIW, I use incandescent lights (both 60w and 320w), 500/1000w halogens, natural sunlight, and occasionally fluorescents (but those don't work for me for swirl-spotting). Hardly ever use the SunGun any more so I'm down to four or five types of lighting that *I* need when doing correction (which I simply don't do much any more). I find the xenon versoion of the Brinkman basically worthless for swirls/marring. I'm experimenting a bit with LEDs but don't use them regularly, ditto for my incandescent-bulb flashlights. Even after doing this for decades, I still spend as much time inspecting as I do correcting, it's *that* challenging for me to spot everything.