You can see what has been changed here:
http://lame.sourceforge.net/history.html3.90.2 is basically the same as 3.91
Basically, really nothing in relation to the alt-presets was changed in 3.92.
And due to some issues about compiler options, etc, I recommend using my 3.90.2 compile. It has been verified by myself to perform exactly as it should. I haven't really done the same thing with the 3.92 compiles most people are using. They
should be fine, but if you want to be sure, use my compile.
I'll make sure that 3.93 is verified to work as it should before I recommend people using it.