It is the shielded nrf24l01+lna/pa. I do not have any scientific test for how well they work.
My real world test is that I was having trouble transmitting directly from my gateway to two out buildings near my house (~150m). In theory, the non-shielded should have worked but it is through several brick walls and they would only communicate about every fifth transmit. After switching the gateway and outbuildings to shielded radios, they receive every transmission.
I had to change the transmit power to low because they do indeed interfere with themselves.
Per our previous discussion, I believe you are correct and they are not completely shielded correctly. At some point this year, I want to be able to transmit from my home to my well house (~150m - brick structure) and then to my front gate (~800m). It is not LOS because of hills and trees.
Part of the design of this enclosure was the idea that you could wrap the interior of it with aluminum foil to shield the radio. Then you mentioned the shielded radios so I thought I would give them a try. Overall, I think the results between the two would be similar.
To most it would seem unimportant for radios to communicate directly with the gateway due to the mash network. The problem I have is, there are mission critical items in my network I want to work. For example, if power goes out: My gateway is running on battery backup as well as my router, modem, etc. If I have a battery operated sensor monitoring the temperature of my baby chicks, it will continue to monitor them. If I rely on a mesh network, and one of the relay sensors goes out, I could loose the sensor monitoring the chicks.