When I bought my TZ back in 2002, it had the regular ROMS installed. I changed over the the 9.4H to gain the pause feature and the LITZ practice mode.
If there were bugs introduced, I have not noticed them, unless it has something to do with how some of the sound effects are played. I have noticed that some of them get shortened, if you start another mode, but this might be normal.
As far as a 9.5 release, I haven't heard anything.