I'd say that is a good practice. If you are anything like me, you will know when your gear is holding you back. I also have the 100-400. I think the 7D is a fine camera, produces great IQ in most circumstances (which for my bird photography is usually in good to evening light, ISO 200 - 1600), and has great features that support bird photography. The 100-400, when properly tuned with AFMA, produces acceptably sharp images most of the time. It should be noted that at 400mm, f/7.1 tends to be the sharpest, while f/5.6 will be visibly soft. Before getting my new lens, I shot at f/7.1 almost exclusively, sometimes stopping down to f/8 and rarely opening up to f/6.3.
I would tune your lens for your copy of the 7D, and start shooting at f/7.1. You should see individual barbs of each feather (a feather is a central shaft, on either side of which is a vane of barbes, which are interconnected via barbules off each barb...you will RARELY see barbules in a photo, but in an acceptably sharp photo, you should see barbs.) There are three things that will soften the barbs of a birds feathers...distance too great, missfocus, bird motion or camera shake. Distance is usually the biggest problem early on. Depending on the type of bird, either learning the right behavior to exhibit that gets you close, or camouflaging yourself to hide in plain side, are was of solving that problem.