Technically, no, they aren’t.
However, you might possibly be able to use your .6 character save with .71. (just tried with my 0.6-450 char and worked, that might be a factor).
Attempt this:
- Start .71, create a random character, get him into the game world (this will create world files).
- Exit out, copy your character.sav from 0.6’s save to 0.71’s save directory.
- Load it up in .71. If you’re lucky, your character will end up somewhere completely random but intact. You might want to carry whatever you want to keep from your old world with you as everything you’re not carrying is gone.