Here's my two cents. Never underestimate the potential for minor and major aggravation that comes with a bike which is tall for the rider, particularly if its also large and top heavy and more particularly if its carrying a passenger.
Try backing up even a very slight incline for even a metre if both feet can't get good contact with the ground. If you're in a tight spot you may not have room to get off and walk it backwards. Try stopping on a surface which has a significant angle to it. You may have to on occasion and its a recipie for dropping the thing. There are all kinds of tight and awkward situations out there, particularly in crowded urban environments, waiting to cause you grief. Slippery, rounded cobblestones, deep curbside gutters and who knows what else.
During a recent trip down the Baja it quickly became apparent that getting off the essentially shoulderless highway, to take a photograph for example, could present a problem. The occasional spot that looked suitable (not too big a drop off the pavement onto a reasonably flat patch of solid looking dirt) could be deceptively unsuitable soft stuff as one of my travelling companions learned when he dropped his BMW. The ability to get both feet flat on the ground in such situations can keep you upright. Once a high bike is moving everything is fine but the slow speed sticky issues can trip you up.
One of my two bikes lets me get flat footed and the other taller and significantly top heavy beast doesn't. I can cope with the latter but the former is really much more pleasant to ride.
Good luck with your decision.