Awesome. The release notes are appreciated too. The previous beta was 12.0.261, so the updates are as below. Especially note the Known Issues, that makes clear that the intention is that superfly renders should look the same as in 11 (if you don't use any of the new stuff). The notes for .272 maybe address the weirdness with the background, too.

Poser 12.0.276 - 2020-11-06

• Shader XML issues triggered by EZDome fixed (#675)
• Vector type input is not a menu choice but a number (#598)

Known Issues (high priority for next update):

• Superfly renders can vary from Poser 11 due to Cycles 2 shader implementations
• Raytrace Preview function not working consistently

Poser 12.0.274 - 2020-11-05

• Queue Manager remote rendering network comms fixes #672
• Queue Manager setting added for verbose logging of network comms

Poser 12.0.272 - 2020-11-05

• WxPython fix, poser.WxApp() no longer crashes. #665
• Cycles Surface image texture now loads in correct projection from Poser 11 to Poser 12. #633, #582
• EnvironmentMap node uses equirectangular as default. flipping values now fixed #618, #561
• Mapping node no longer has duplicate fields. #615
• SuperFly Raytrace Preview has no longer Depth of Field turned on. #663, #607 (edited)