Also, the 256 uses 2x128 drives while the 512 uses a single drive, so you even get slightly slower storage with the upgrade. The base model is a great deal.
This is true for the Mac Studio but not for the M4 Mac Mini -- they all have a single storage slot and the only difference between the 256 and 512 models is the model of the NAND chips.
You're right thanks. The change was to 2x128 NAND for the 256 drive from the previous generation, not 2xSSD.
Do you have a source on that? It's not what I've read elsewhere, but I'm having trouble finding anything specific.