Some interesting observations and viewpoints. I'm accustomed to narrower bars (trimmed to 46 - 50 cm / 18 - 20") so find the lower flat very comfortable as my basic more upright position with both setups (and the same reach distance and height in relation to saddle, via the stem riser in the inverted position). Can't use a helmet mirror, my eyes don't focus well with one and find it distracting. I don't mind the mirror where it is but will try the suggested lower curve position as outlined in the 3rd picture from Sheldon Brown.

My flat bar road bike, showing the 3 positions I've been using with bar ends.