Night HDR's by varying ISO rather than shutter speed?

Canon 5dm2 with auto-exposure bracketing up to 2 stops (-2 / 0 / +2) accomplished by changing shutter speed

I’ve been pondering whether there are potential advantages from making night-time HDR’s by varying the ISO rather than varying the shutter speed. Generally with shutter-speed based HDR’s made at night, I typically use the camera’s non-bulb maximum of 30 seconds, and then figure out the appropriate f-stop and ISO. With an UWA (ultra wide angle) lens like a 14mm, I generally get enough DOF at f5.6 or f8. So the exposures might be 2 sec for the highlights, then 8 seconds for the mid-tones, then 30 seconds for the shadows. The exposure decision for the shadows determines the choice of ISO, which seems sub-optimal for the mid-tones and highlights. With a tripod and a static subject that isn’t moving, it seems like the final HDR might be a bit improved with an exposure bracket of:30 sec + f8 + ISO 100 for highlights30 sec + f8 + ISO 400 for mid-tones30 sec + f8 + ISO 1600 for shadows My early experience with a few of these is the disadvantages include:* cameras aren’t designed with AEB to work this way* takes longer with more steps that using AEB* handling of camera to change ISO could slightly change position of cameraFeedback appreciated on pluses and minuses to this approach.