I rip CDs to high-quality OGGs for desktop play and lower-quality MP3s for my phone. I really appreciate that abcde makes this faster and easier than it was when I was using jack.
I keep them in separate directory trees to make it easier to select files for playing or copying to the phone.
As a Linux user who goes back to the days of punched cards, it's no big deal for me to type the commands to split the files into ogg and mp3 trees, but it might be a hassle for others.
It _looks like_ all you need to do is use $OUTPUT instead of $OUTPUTTYPE when constructing file paths, but I may not be fully understanding your code.
As you seem to have figured out, you need to use $OUTPUT.
$OUTPUTTYPE is the LIST of output formats that will be encoded.
abcde loops through the $OUTPUTTYPE list encoding each format.
$OUTPUT is the current format that is being encoded.