Machika and I were discussing front pannier loading the other day. One thing to watch out for is a change in the steering on loose gravel, should you encounter roads like that. Both of us have had bad experiences with the front tyre washing out when riding with front panniers -- me with them set up with ones of the rear too, and Machka with panniers only on the front. In both cases, we were using low-rider style racks and our bikes are of entirely different sizes and designs, albeit with 700C rims ranging from 25 to 32mm diameter.
We've both found the problem of wash-out -- something like the front tyre losing grip on an oily wet road surface -- resulted in us being dumped off the bike. The problem did not exist with just panniers on the rear and a handlebar bag up front.
Sooo... I would suggest lightly loading front panniers if you are expecting to encounter distances on gravel roads with no alternative route on sealed surfaces, and on the style of bike described.