It was my understanding the XSX SSD is 2.4GB/s (Raw), 4.8GB/s (Compressed) and the "over 6GB/s" referred to the speed at which the decompression block ran.
What is unclear to me at this point is whether or not the 4.8GB/s Compressed figure is a hard limit somewhere in the I/O pathway and the decompression block's >6GB/s simply provides overhead. Or if it is an average and the entire pathway can actually move >6GB/s end to end in ideal circumstances. I'd hope and assume it's the latter for the sake of Xbox devs and end users.
If it is the latter; I'm surprised MS didn't capitalise on it and state "2.4-6GB/s", or more honestly "2.4GB/s (RAW), 4.8GB/s (Average Compressed), 6.0GB/s (Peak Compressed)"..... saying that, their official spec sheet only says 12TF when they have 12.15TF, so perhaps they're playing it a little more reserved.
Regarding Sony and PS5, the way it was worded makes me pretty sure it's 5.5GB/s (Raw), 8-9GB/s (Average Compressed) & 22GB/s (Peak Compressed); that 22GB/s being peak end to end throughput in what are likely very rare circumstances and as a result of a limit in the decompression block. Cerny said "..the unit itself [kraken decompression block] is capable of outputting as much as 22GB/s if the data happened to compresses particularly well".
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Now for a bit of levity, according to youtube closed captions -- while checking for the quote -- it turns out the unit can move over 5GB of crack a second; not to mention "format input data"..! =P