ProRes vs .mp4 or .MOV for acquisition.

The new Lumix GH5 records 10-bit 4:2:2 internally at data rates of 100, 150 and even up to 400mbps once the firmware updates kick in later this year.
The Atomos Ninja Inferno records 4k 10 bit 4:2:2 in ProRes at a MUCH higher data rate. (for an additional cost after purchasing the GH5 camera)

My question is this: will recording Atomos video at 4k ProRes LT give me better quality .vs 400 mbps 4k internal Lumix GH5 using .mp4 which will then be converted by FCPX into ProRes upon ingestion into my FCPX project anyway?

Does that make sense? Since I'll ultimately end up with 4k ProRes LT to edit with in the project, is it OK to use the Limix internal mp4 codec to acquire and then have FCPX convert it to 4k ProRes LT afterwards?

Reason being: If GH5 internal .mp4 is OK for acquisition in the beginning ant then looks the same in the end (once FCPX converted it to ProRes), it will save me the cost or purchasing an external Atomos Ninja recorder just to get 4k ProRes LT files in the first place.


Thanks in advance,

Chris