Since this is mostly a road bike, and you seem comfortable with drops, I can't see any reason for flat bars. If you need a wider bar for control offroad, first I don't think it is really all that big a deal, but I would still go for wide drops. There are several drops available out to 60cm, so you can have your cake and eat it too.
The only problem with drops on a touring bike is that if you use road levers it creates some technical challenges for rigging the brakes, but we have all been there and eventually found something that worked.
I think your crank gearing is far too high if you ever hit the noted combo of "even heavy) touring, with ability to go a little offroad". You want standard touring stuff for that which is 46-36-26, and 11/13-30/34.