Have you also considered the Tamrac Expedition 5.? It's just about the same size as the mini Trekker but has a much better build-quality to it. For example, the handle strap is much more substantially built and padded on the Expedition 5 but is a measely strap on the mini-trekker (the main reason, along with disappointing quality, I returned the mini Trekker and exchanged it for the Expedition 5. My 1D2 with the 100-400L w/hood attached, 10D w or w/out the grip, 580EX, 24-70 w/hood and Sigma 17-35 and hood all fit nicely in the Expedition 5 main compartment without it bulging out at the seams.
[edit: BTW, I just came back from a 2 week vacation in California and the Expedition 5 fit nicely under the seat in front of me.
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