The Dell AW2725DF has decent HDR brightness. Very small highlights get particularly bright and pop against the rest of the image. However, larger highlights don't pop nearly as much. Additionally, the monitor doesn't follow the EOTF curve very well and is too dark in most scenes. It also has a slow roll-off at peak brightness, so highlights don't get as bright as they could if only your computer was tone mapping.

These results are from the 'HDR Peak 1000' Smart HDR mode with the Brightness locked and Console Mode off. You may prefer the 'Custom HDR' Smart HDR mode, as it has a good EOTF cutoff, as you can see here, and you can customize color settings. However, 'HDR Peak 1000' has better brightness.

Interestingly, 'HDR Peak 1000' isn't the brightest HDR mode in all scenarios. Except for very small highlights, the 'DisplayHDR True Black' Smart HDR mode is actually brighter. However, during real scene testing, 'DisplayHDR True Black' brightness is 382 cd/m², while 'HDR Peak 1000' brightness is 407 cd/m². You can see this in more detail below:

DisplayHDR True Black
  • Peak 2% Window: 457 cd/m²
  • Peak 10% Window: 457 cd/m²
  • Peak 25% Window: 366 cd/m²
  • Peak 50% Window: 310 cd/m²
  • Peak 100% Window: 261 cd/m²
  • Sustained 2% Window: 453 cd/m²
  • Sustained 10% Window: 455 cd/m²
  • Sustained 25% Window: 363 cd/m²
  • Sustained 50% Window: 308 cd/m²
  • Sustained 100% Window: 259 cd/m²