Unfortunately the mentioned additional [CHR$(13)&]CHR$(10) is not the only issue: because of utf-encoding of text-write-operations, the output differs in various ways. Therefore TEXT.WRITELN normally is not an alternative...which is a pitty because of the mentioned speed differences.
For-in our days common- filesizes of several MB, BYTE.WRITE.xxx is almost useless,because of unacceptable long time needed for writing.
For small files the time difference is negliable, as in example below (compare size/content of output-files)
file_in$ = "meow.wav"
GRABFILE file$, file_in$
BYTE.OPEN w,fid, "meow_byteWrite.wav"
BYTE.WRITE.BUFFER fid, file$
BYTE.OPEN w,fid, "test_byteWrite.dat"
BYTE.WRITE.BUFFER fid, "a"
TEXT.OPEN w,fid, "meow_textWrite.wav"
TEXT.WRITELN fid, file$
TEXT.OPEN w,fid, "test_textWrite .dat"
TEXT.WRITELN fid, "a"