I guess my feelings stem from the fact that image quality is much, much more important to me than the AF system.
And what if the AF system is the key factor that lets you GET the shot in the first place? How valuable is IQ if you can't lock on focus, track, and capture the subject your interested in? For that matter, how valuable is IQ if you can't fire off enough frames in fast enough succession to get your now focused (thanks to the AF) subject in a worthy, intriguing pose? IQ is an incredibly subjective thing...just having sharpness and low noise means nothing if the photo is uninteresting or out of focus.
Advanced AF systems and high frame rates (both things the 7D offers) are critical to many types of photography, and just as important (if not more important in some cases) as IQ.
I have the 7D and really like the camera. I only wish it did better in low light. I feel like this model should perform better in IQ and low light performance compared to the rebels. Now I realize you get the magnesium body, higher fps and better focusing system. But it has always seemed a little wrong that the 7D and maybe the 60D weren't more of a step up from the rebels. Maybe one or both should have gotten a slightly bigger sensor.
Does anyone else agree?
All things being equal, while the 7D noise at high ISO (1600 and above) can look rather crazy when pixel peeping, keep in mind the resolution of the sensor. Pixel-level noise at ISO 1600 and even 3200 doesn't mean all that much when you have such high image resolution. In my experience, the 7D's sensor performs quite admirably at high ISO settings, and the noise is quite easy to clean up. I've also found that its preferable to leave a little bit of noise in place when printing as it helps improve gradients, background bokeh a bit, etc.
The value of the 7D does not really lie with its sensor, though. Its a camera designed for action in fairly rugged situations. The true value of the 7D is the fact that it brings to the table one of the most advanced AF systems for APS-C, and a pretty high frame rate for its resolution. When you need to shoot moving subjects at high speed, the 7D will perform extremely well, and is only really surpassed by Canon's 1D line. The one benefit the 7D has over the 1D line now is its smaller
sensor...which helps extend the reach of any given lens when compared to a similar APS-H or FF sensor (i.e. using a 600mm lens on the 7D would be like using a 960mm lens on the 1D X from a framing standpoint.)
Here are some shots of birds in flight, taken on an overcast day near sunset (fairly low light, low enough that I was REALLY pushing the image stabilization of my 100-400mm lens even at high ISO), with a Canon 7D. ISO ranges from 160 to 2000, and all of them are keepers (there definitely is
noise in the ISO 1250 and 2000 shots, but when scaled to a reasonable web size or printed, its a non-factor
...the shots still look great). If it wasn't for the 19-point AF system and 8fps, most of these shots wouldn't exist: