Interesting article Doug
Have taken the liberty of condensing it into a hyperlink
here.
It does seem the negatives outweigh the positives, specifically that oil vaporisation due to higher temperatures increases the presence of droplets on valves in the first place, not so much that they are not washed away by upstream fuel. I read during the development of the Ford Cyclone engine direct injection was considered and even used on a prototype but their engineers eventually chose port injection.
