Since you got me thinking about your comment Saxman, I dug out my 2 Group RAF history. They flew the 25s in the ETO. The majority of their B-25s were Mitchell IIs which were C/D models like the glass nose version AH has. They did not have tail guns. They got their first Mitchell IIIs into action in November 44. The comments were that it was not as popular with crews as it was heavier and not as responsive on the controls as the earlier version.
They had a number of Mitchell IIs with close to or more than 100 missions, flying as 1944-45 level bombers. I guess escorts must have been the key