XL2546 and XL2546S DyAc brightness is similar.
However, 0.5ms GtG will reduce strobe crosstalk for DyAc.
So I'd say go for the XL2546S over XL2546 if you're worried about reduced strobe crosstalk at higher Hz (above 180Hz).
At max-Hz, DyAc strobe crosstalk is slightly worse than ULMB crosstalk, unless you reduce refresh rate to 144Hz or 180Hz. The extra oomph of faster GtG will allow you to use a higher Hz before being distracted by strobe crosstalk (assuming you're sensitive to strobe crosstalk).
Also, be noted that strobing doesn't always help all games, it mainly helps eye-tracking situations during fast motion.
Do not forget to raise mouse DPI with strobing! (And upgrade mouse/mousefeet/mousepad if needed)
-- Raise mouse DPI (1600dpi+) and then lower in-game sensitivity. Strobing benefits from high mouse DPI, especially for slow-speed turns/medium-speed turns. This helps mouseturns become TestUFO-smooth.
-- Strobing amplifies visibility of mouse microstutter. There is no motion blur to hide tiny mouse microstutter. This is why many sees benefits in TestUFO but not in many games. It will help aim control (the esports companies are advertising strobing as an aim stabilizer during spraying bullets), but if you want to see clearer during mouseturns, you want high DPI. You need mouse slow-turns to become as smooth-motion as strafing left-right, in order for mouseturns to benefit a lot from strobed modes.
That's why I recommend 1600dpi+ (or higher), with a recent good mouse sensor, clean mouse feet, high-resolution mouse pad, etc. Yes, --- Yes, most esports players use 400dpi. That's perfectly fine without strobing on low-Hz monitors. But if you use strobing during FPS, or use ultra-high Hz (240Hz or 360Hz) then there's advantages to be had at 1600dpi+ 1000Hz+. I'm STILL waiting for mouse manufacturers do release a good-2000Hz good-3200dpi mouse, Logitech/etc "havent" yet discovered Q/A beta testing with strobe backlights yet.
-- 1600dpi can be worse than 400dpi if your mouse feet are old/dirty/scratched or with cheap mouse pads. Fix that, then you can get even more additional competitive advantages with strobing/DyAc/ULMB/etc.
<Technical>
There is a noticeable difference between 1.0ms GtG and 0.5ms GtG in reducing
strobe crosstalk. This is very important for 240Hz max-Hz strobing, since slow GtG requires more refresh rate headroom below Hz to eliminate strobe crosstalk (Because you need to hide GtG pixel response in dark periods between refresh cycles,
as seen in high speed video).
</Technical>
*Yes, GtG ratings 0.5ms vs 1.0ms may not be real-world. However, 0.5ms-vs-1.0ms best-case can still more-or-less translate to 5ms-vs-10ms average GtG100% realworld. That's still a huge difference. Historically, GtG ratings have been reasonably okay relative-predictors of strobe crosstalk (as long as they are honest VESA GtG90% apples-vs-apples ratings). That's why we're big advocates of faster GtG, even towards honest GtG <0.1ms, in the refresh rate race to retina refresh rates. GtG needs to be a tiny fraction of a Hz to prevent interfering with the clarity of the refresh rate. See Pixel Response FAQ: GtG versus MPRT