i was going to take the pi 5 too, but after the 3 and the 4 i bought a mini pc instead of raspberry pi 5 with nvme and 16 gb of ram, imo is still to early and too many accessories that you need to spend more money and they are still in development, not all the accessories have been released yet for the Pi,5, its an amazing cheap mini pc but with the same price you can get absolutely better, i bought the Beelink s12 pro
The default case is better i have tried the active cooler in it but due to less heat decipation in case the pi heat too much then before "if put the active cooler don't put the case"
I thought about doing this but wondered whether the tiny gap between the lid and case is big enough to let the blower intake air. It's designed for the case fan, but the active cooler is recommended uncased for airflow. I don't know
I would recommend leaving the lid off during use. However the temps don't get too hot. During use it doesn't go above 60C with the lid on, and that's with the system being stressed
Seems like doing this mod would allow for the fan to recycle its own exhaust. Using the clear lid and fan helps to ensure fresh cool air outside the case gets pushed in and hot air will be pushed out due to the positive pressure from the case fan.