Ok, to make things a little clearer, as I understand it, the auto-reset firmware is still RPC2 but the number of times you can change the region resets to 5 when you reboot.
Which type of firmware to use depends on what you use your drive for most of the time.
Now there are some DVD movies which when you try to play them, will refuse to play if your drive is RPC1. These are not that common. I have not encountered them myself (I borrow DVDs from a library fairly often). However, if you want to be absolutely sure EVERY movie will play on your drive, you will want your drive to be RPC2. So if you mainly use your drive for watching movies, you probably want the auto-reset firmware. As macrobe pointed out, so far none of these movie companies detect whether you are using auto-reset or just plain RPC2 so it should be fine.
On the other hand, certain DVD ripping programs have a tougher time cracking certain copy protection schemes if you use RPC2 firmware. That isn't a problem with RPC1 firmware. So if you mostly use your drive for ripping DVDs, stick to RPC1.
Comments, corrections etc most welcome. Am still learning too.