i have the 70 version and im very happy with it. i got it for light beach work and its a gutsy little reel. it managed a double dogs for me without any dodgy noises or croaking. if your buying online be carefull as ive heard the 40 is tiny, smaller than other abus marked the same size.
the "braid spool" is a bit of a gimmick, its just 2 grooves with rubber bands in them, the braid digs into the bands and wont slip. i does work but a bit of insulation tape and a bit of mono will do the same thing without you having to put a full spool of braid on. if youve gotten spooled by a big fish then it might be necessary
as for the 5.1:1, every 1 turn of the handle makes the spool rotate 5.1 times. the ratio would be the same thing i presume.