I use full front and rear rack setups. I put the rack bag on the rear rack. Heavy items go low in the front low rider panniers, lighter items in the rear panniers, personal effects in the handle bar bag. I put a small tent on the top of the front rack if I need more room in the panniers. Depending on your clearances you may not have room on the front rack for a rack bag and a handlebar bag. I probably would, but I ride XL frames (62cm-64cm). In general terms having weight higher up on the bike will affect steering much more than when it is lower down. Get the rack and try strapping a 10# weight to it and see how much difference it makes. One LBS that I visited years ago had a full set of bags and a bunch of small sand bags that they would load up a test bike with so you could get an idea of how weight distribution worked and the differences it could make.

Aaron