I use the Arkel laptop pannier, and I think it's great. I don't like having anything on my back. I'd rather have the bike carry the weight. Plus, when the weight is in panniers, the center of gravity is lower, which is much better in terms of maneuverability.
+1
I felt way too top heavy when I tried riding with a packpack
I'd rather be swimming...biking...running...and eating cheesecake...
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2008 Cervelo P2C Tri bike
2011 Trek Madone 5.5/Cobb V-Flow Max 2007 Jamis Coda/Terry Liberator
2011 Trek Mamba 29er