We have been using ZW for six months and to great effect, thank you very much the ZW Development Team.
I have been conservative with backgrounds and fonts in order to maintain maximum visibility, especially for those who may have a visual impairement. I have discovered a few things:
a) Verdana is a very readable font, particularly for dyslexics.
b) Emboldening does not make text more readable, better to not be bold and use a larger font size.
c) Shadowing and outlining should be avoided.
d) The visually impaired can generally read black on yellow best.
I was extremely pleased to be told this morning that a visually impaired lady in our church can actually read the screen better than the alternative large print order of service/hymn book.
I hope these discoveries help!