Boy do I like front panniers!
We are presently on a tour and this is the first time using front panniers as we decided to not take the BOB trailer. I am REALLY enjoying the added stability that they provide.Especially on long downhills. I think that the front panniers and the change to 32mm tires has really made the ride more enjoyable.
We just got back from two weeks bike touring in Austria on our triplet. We've always used front and rear panniers when touring on the tandem, usually with the f/r weight being about equal. Due to the overall weight of the triplet (I figure we were about 550 pounds +/- fully loaded), I moved more weight to the front panniers and it made a huge difference in how the bike handled.