HI I haven't used the Bernette 20, but basically anything "Bernette" is not a real "Bernina" and I wouldnt recommend it. I have had an older Bernette front bobbin loader model and it never sewed a quality stitch! You would be much better off upgrading to a newer Janome. I love the Janome Decor Excel 5018. It is so easy to use, not computerised so still has the reliability of the older Janome machines, is quiet and does a lovely stitch. Not sure if it is still available?? But if you can find one even second hand you can still get the manual for it at www.sewingmanuals.com.au
If you cant find the 5018 I think the next one up is the Decor 5124 Pro. Very much the same but more stitches I think.