I think removing the interior mirror is depriving you of one of the sources of information of what is going on around your car. Sure, it takes away a little of the forward vision, but who can say it is so much that it is a safety problem. In addition, the door mirrors are generally convex (should be, at least - as the flat ones are rubbish and ought to be changed) and thus give a distorted image of sizes and angles. Then the flat interior mirror is a useful addition and correction to that, not least when you are reversing. Bringing in trucks and motorbikes I think is irrelevant - they do not have a choice. However, reversing cameras are becoming more and more frequent, not only in trucks but also sedans. So for me, convex door mirrors, and a flat interior mirror. Safety first.
