I'm running both Poser 11 and Poser 12 on my 2017 Intel iMac with Big Sur (11.6.1) and my M1 Max MacBook Pro with Monterey (12.0.1). I can confirm both versions of Poser run super smooth on both operating systems.

What @an0malaus said about multiple displays is true. If I'm using Poser 12 on my primary iMac display the rendering progress dialog box sometimes appears on my second display. Same with the 'Image Source' dialog box on the Image Map node in the Material room. These are minor inconveniences in my workflow. Otherwise I'm really enjoying the stability and speed of Poser 12 on Mac.

PS. Rendering with Adaptive Sampling in Poser 12 is noticeably faster on the M1 Max. I can only imagine how fast it will be if/when we get Metal support!