Well job looks very nice. One small thing though, the variable speed blowers require a min. Of 18 inches of the plenum height to be the same size as the opening on the top of the unit. The reason why is because the blower needs to have the resistance of the pressure of the duct as it try's to find the proper speed. The transition ( while nicely done) will not allow this to happen and you will experience harsh " huffing " noises and uneven airflow. This can cause the loss of capacity and motor damage. Other than that nice job.
Perhaps they use a different blower than geocomfort. I have also had the same problem on the climate masters. Last one I found was done with duct board and it sounded like someone was moving furniture around upstairs as it ran.