Wow, good question. I'm not sure. I really wouldn't worry about the warranty. I mean, I'd recommend using the codeguys firmware for LiteOn drives. It increases the rotations per minute (allowing for faster burns) and allows your to further over speed your media (ex. 8X media can be burnt @16X). However, even though it works flawlessly, it does void your warranty.
Really, the drive is only about $25-$30. If it dies out of warranty, it's not that big of a financial loss. The convenience of altering the EEPROM and using hacked firmwares is more than worth losing the warranty in my opinion. Plus, warranty repairs take FOREVER. I can't remember the last time that I utilized a warranty.
Another option, if you're that worried about the warranty, is to install software that executes at start up and changes the booktype for you every time you restart. I don't remember where to get it, though, because I don't need it. :p: