Yes I do, but not for long walks. I have a Gura Gear Kiboko. Hassy fits comfortable in left flap with four lenses. Sony Alpha 99, 24-70/2.8 and 70-400/4-5.6 goes into right flap. Quite workable, albeit heavy. Add to that an ultra light CF tripod from RRS with a leveling bowl and an Arca Swiss D4 to make it heavy.
I went on four hour hike in the Dolomites, than I left Hassy stuff where I lived and just took two Sony's and four lenses.
Do you intend to keep carrying around 2 systems?