That is really quite irrational, you are already reading and writing from and to the internal flash each time you update your OFW and CFW,
It's even worse than that, as you read and write from flash every time you turn your PSP on and off. (Don't believe me? Do a nand dump, turn your PSP off, turn it on again and do another. Then check the hash values.....different!) I know it's crazy, but it's just an insanity i acknowledge and work around it!