That I can understand, that applies to all other handsets..

I'd never recommend changing the product code.. Thankfully flasher kind of removes the need to do so. Why else would you want to change it other than to get a different firmware?! Dunno...

Installing alternative firmware doesn't seem to care about product codes if using flasher..

If this rule applies to the N900 flasher should at least have a warning (using this option will void your warranty) It is fairly dangerous to provide an end user tool that voids a warranty without warning..

Maybe that should be raised as bug for flasher.. then again, they might take the functionality away for those who are already outside their warranty (like European buyers who bought from the USA)

Changing product codes... bad... changing firmware... also bad? dunno