The dangers in extras-testing and extra-devel are wildly exaggerated.

But so is the inconvenience of flashing. Flashing is an essential tool. You need to back up your data and be ready to flash as necessary to use your N900 properly, meaning to be able to use apps that are in extras-devel and testing without fear.

I have not been paying attention to whether apps are from extras-devel or testing from day one, with no bad consequences.

Even newbies who got here yesterday should learn how to flash their devices, because they might need that ability. It might be a pain to a certain extent, because Nokia apparently never understood how to deal with 64-bit Windows 7 -- I have seen dozens of threads about it, and even seasoned veterans instantly give up when they see it and insist that people install some version of Linux to flash. That is ridiculous -- it should not be necessary, and it seems that Nokia has not fixed that problem, though they have had a long, long time to work on it.

But you need to be able to flash. And in my opinion, to use your N900 properly, you need to use extras-devel and testing from time to time.