This I'm using with astroberry/stellarmate since october 2020. Wifi works with that setup, in my pc room (one wall between raspi and wlan repeater) I have 10Mbyte/s download speed...
What I observed is that when I'm using the raspi in house at 25°C sometimes the temperature goes up to approx 80°C (e.g. when updating), with thermometer icon blinking... Maybe for summer it will be better to get a better cooler...
My biggest concern about the open-ness of that case would be accidentally touching the GPIO pins (doing that has a really high possibility to fry the pi from even small static charge on your fingers). You'd want some sort of GPIO header cover.
I use it as it accepts a M.2 SATA SSD, which were particularly cheap at the time, and it improves performance quite a bit over a normal SD card. I also like it as all ports now go to one side, which helps with cable management.
Sorry for the late response, I was out of business some time
I had the Raspi with the changed case in use now for several sessions. I also had some concerns regarding the open GPIO pins. I solved that with a piece of foam which I just put on the pins.
Last week I had about 15°C to 20°C in the night and the Raspi was working with kstars and PHD2 guiding at 51°C. This I had with the old case during winter
Till now I had no problems also during at least two foggy nights, where the telescope was wet afterwards. I think due to the "heat" of the big heat dissipator (which coveres the whole Raspi) there was no fog on the raspi (dew heater).
I run two Astroberry rigs each in Flirc metal cases. Just make sure to put the case top towards the metal elements of your mount to give the WiFi the best chance to work through the case plastic bottom. The case acts as a heat sink from the RPi processor chip and does get a little warm but outdoors in the dark has never overheated and resulted in throttling.
Currently running KStars/Ekos/Indi on two Raspberry Pi 4Bs 4GByte under Raspberry Pi OS thanks to Astroberry
Two mounts, two Fracs, a Newt and a Mak and a couple of OSC cameras.