I don't fly red much but I find the bf110 really annoying as the AI flies it far too well making shooting difficult. As I've said before if the bf110 could evade that well in real life it would have won the Battle of Britain.
As for the Bf109 cannon, if they were that ineffective in real life they would never have replaced the 4 MG's on the Bf 109 E-1. I am looking forward to getting a bf109-E1 with 4 MG's rather than the cannon!