I am sorry, canon a3 with waterbased inks and bn-20 shouldnt even be compared.
yes bn20 is slow but it offers three speeds. Only highest resolution printing is that slow. If you go one notch down it will speed up about double without huge quality sacrifice. Plenty enough to make product that can be sold.
Bn20 will do for doming as i used it and i loved it.
Quality is great and is fast enough. And.... it cuts as soon as it finish printing :)
Of corse there are more expensive options out there but if you only have 5k and you want eco solvent than go for it.