The current release of the program (v1.2) does stop responding while it is performing the conversion. The next update will fix this problem.
By default, this program utilizes the ConvertData executables that come with the game. So, if you have the new beta (1.19), you therefore have the new beta ConvertData exes, and I have no idea if those are backwards-compatible with files from the current stable version (1.011).
Hopefully this weekend I will be able to get a post up on the program website that talks more about some of the new features coming in the v2.0 update. Progress has been good, and I don't have too much more work to do on it.
EDIT: Overview of what's coming in v2.0 is now up at the official website (link in the OP)!