Originally posted by Docrwm Don't know much about the Canon so I'll ask this - how is it in low light? Seriously, many of my son's games are at night and the lights are not University stadium quality so the lighting is a bit less than perfect. Part of why I got the K-x is because of its outstanding low light performance. I just got through shooting soccer at 6400iso after shooting Softball for my daughter earlier that day at 200. Just asking.
The Kx is nice but it's not going to come close to night action shots at high ISO as a 7D...it simply does not possess the power under the hood. Here are some discussions of the high ISO performance of the 7D:
Those are from one of the best sources for Canon info on the web so any of your questions can be answered there...you'll need to do your own comparisons but such is life. The K-x is a super body with a nice sensor but the 7D is simply in a different league...and that is no knock on the K-x because for many of us the difference is not going to be that much. However the features such as AF-C in low light of night sports of the 7D, well, the K-x, K20D or even the K-7 won't come close the the keeper percentage. Now whether that percentage is really that big of a deal, easily to the tune of a good $1500 difference in cost depending on lenses used with each body only you can decide for yourself.
Figure you are going to drop between $1700-$2500 for a 7D and a decent lense that can justify the sensor's resolving power....and remember the center AF point on the 7D is an f2.8 point compared to, I seem to recall, an f5.6 on the K-x and K-7...I also read in one review that the K-5 also has a slower center AF point of 5.6 as well which is sort of a let down, I think? But really I have no idea for sure and we all have no idea what the final body will deliver...
But you asked a good question...it's always wise to keep looking around as long as you don't feel you have something that is "not good enough" because any of today's modern DSLR's are going to deliver super results. I feel the K-x is a bargain but then again I am one to not believe in the "bang for the buck" when applied to DSLR's because, as a rule you need to buy the best body AND best glass you can afford. In fact buy glass that is better than the body so that glass is still relevant in a few generations. Hence why so many love the FA limiteds as well as the FA* or DA* series glass.
One last thing, the 7D craves FAST high end glass (for your kids sports I say get a EF70-200/4L IS or non-IS [a true steal at between $600-$650]. Both are amazing and the 7D's ability to shoot high ISO and the faster center AF point makes for a super combo...you could even look at the EF70-200/2.8L non-IS which is the same price as the F4-L/IS version...but the ability to shoot higher ISO is going to let you use higher shutter speeds w/o worry about significant noise issues.) in a way the old 20D/30D/40D/50D bodies did...ignore the 60D it's not close the the IQ of the K-x let alone the new K-r or K-5...
Anyway, this might piss of some people but I just wanted to answer your question. I am NOT saying to switch because I sense the K-5 might be able to deliver for your needs if you have some nice Pentax glass already. If not, then.....welllll, perhaps a look at the 7D is very worth the time to wait...