I'm encouraging "new platforms" to use 0x2F for the lock bits, which adds the ability for the sketch to read the bootloader area (and, in particular, see the Optiboot Version number.) I'm pretty sure this is pretty safe (but it wasn't safe enough for the Arduino team to change on Uno...)
(This is actually less important now that the version number is also transmitted via the bootloader protocol. But it's still nice, IMO. It permits sketches like "Fusebytes" to report "useful diagnostic information" about the state of someone's Arduino.)