I’m glad you pose this question, Shawn. Personally I default to finishing existing projects within the Blender version it was created unless the new / alt version of Blender offers crucial features needed to complete the project.
My only real concern with upgrading to 2.9 for the backhoe project is that we would all need to do it. If I updated the master assembly and a 2.83 contributor opens it, the data loss warning is bound to flash. Could cause confusion compared to sticking with 2.83.
When this happens during my freelance projects we typically play around with the new version on non-production files to decide if we want to upgrade sooner or later. I’d recommend that for us too: Play with 2.9 for a week then decide if we all want to upgrade the project to 2.9.
