It's a problem for me too. My first Morgan, 2002 4/4 with stud hood later converted to Simmonds hood was comfortable to drive on wet roads. Rain really did go over the top and the inside of the screen remained dry. Current car, 2011 plus 4 with easy up hood is a pain in wet weather. Rain still goes over the top, above a certain speed, but the inside of the screen and the mirror rapidly get covered with mizzle. Both cars have spare wheels and are usually driven with side-screens if the roads are wet. The difference in shape/size of the screen appears to be the problem.
I have experienced this with our car on occasions yet on a long drive through Switzerland in light drizzle it did not happen. It was night and at first I was looking for a place to stop and put up the hood but then we realised that we were not getting wet so we kept going. Nothing came onto the inside of the screen yet on other occasions we have been more-or-less compelled to put up the hood, not just to keep dry but to stop having to constantly wipe down the inside of the screen.