Actually, it is still true. hexdump has some confusing format options... what you were using was converting it to little-endian first before printing the hex representation, which really messed with gzip. Try this:

    $ hexdump -e '"%x"' < american-english | gzip | wc -c
    463871
    $ hexdump -v -e '/1 "%02x"' < american-english | gzip | wc -c
    302515
    $ base64 < american-english | gzip | wc -c
    415737