Its really tough to compare the two since they are so different, but I have some time to kill so here goes. I have used the 10D for about 4 months and used a SD9 for about 3 weeks.
These are just general observations and dont get into super specifics like flash sync etc. Also take them with a grain of salt. These are good points and bad points as they affected me.
I would say generally
10D pluses
The 10D body is built better. Sturdier.
The 10D has a super battery good for about 500 shots. I have never run one down. The SD9 has a two battery system, but its not really a problem.
There are a lot more lenses available for the 10D including a few with IS.
The 10D has very useable high isos. 800 is about like the SD9 200 as far as noise, but you can underexpose the SD9 quite a bit and pull it up in processing so its almost like a higher iso.
Low noise.
Colors are good.
Its got jpeg if you ever want to take a few snapshots without the raw hassles.
Its got a mirror lock up
It can meter through a manual lens
Ir sensitive if you are into that, but the IR sensitivity is not as good as a Sony 717.
10D minuses,
Its slowwwww on startup and wakeup, about 2 sec. This was a real pisser for me. I felt like I was shooting my E20 again, that by the way took sharper pictures. (My 717 is super fast start and wakeup and blows my 10D away.)
Super super soft images. Too bad it does not have a removable AA filter. Detail that is lost can not be regained no matter how much you sharpen. My $640 sony 717 take pictures that carry almost as much detail as my 10D. I could not believe it !
Very sensitive to blowouts and over exposed skys. This camera definatly needs more dynamic range. You really have to use grad nd filters or use a polarizer and watch the histogram very carefully to get a good outdoor exposure on a bright day.
(those are the 10D big ones that are killing me)
There seem to be some quality control issues with focus and exposure, but my camera focuses right on.
L lenses cost a small fortune. Major bucks. Maybe like 3-4g or more to shoot from 16mm - 500mm.
Raw software is just okay, so plan on spending another $100 on capture one. Also while I am thinking about it I have not had very good luck sharpening 10D images without producing sharpen halos, so you need to invest in a sharpen program like nik (expensive) or develope a good routine yourself. Mind you 10D images are okay out of the camera for small prints
No spot meter (what were they thinking)
SD9 pluses
Number one has to be super super sharp images. I would say in enlargement terms comapred to a bayer sensor with a AA filter its equal to about a 8 or 9mp sensor, but not up to the 1ds. I have done big crop enlargements and the detail carries very well if you can get past the stair stepping. Unless you want to spend $5000-7000 on a camera body you are not going to find a sharper dslr body. You will never have to use USM on these files, unless they are out of focus.
Great raw converter. One of the best. Funny it is very similar to capture one pro.
Its fast all around. A lot faster than the 10D.
Nice body with simple menus.
I found the focus to be acceptable.
Cheaper lenses. You can buy a 50-500 and a 15-30, (both great) and you have just almost covered the entire shooting range I mentioned above (if you can handle the 50-500 weight. its big)
Its got a mirror lock up
It can meter through a manual lens, kindof ?
SD9 minuses
Low iso, but like I said above shoot -ev........
Noisy camera, but personally I would rather have the noise and more detail. Beside you will never see it in a small print.
Halos around reflections. This was the one that really got me and some cameras seem to be worse than others. Mine made blue halos, others make gray halos. Who knows what causes that. It seems like they should be albe to fix this with software.
This camera like the 10D is also very sensitive to blowouts and over exposed skys and light areas. This camera definatly needs more head room. It is about the same as the 10D. You have to spot meter the lightest area and lock then bring up the dark areas in photo pro. Also a Grad nd or polarizer helps too on bright days.
(those are the big ones for the SD9)
Not really a minus but you have to use EX lenses.
Colors are slightly flat, but thats not a big deal and is easy to correct with photo pro.
1.7x crop is a killer if you like super WA like me, but I dont even like a 1.5x crop. For telephoto work its great.
No jpeg, but that did not bother me since I have a 5mp P&S and I shoot my dslrs in raw all the time any way.
Not IR sensitive.
No flash (not a biggie)
Also there are a lot more pluses and minuses for both the 10D and SD9. Scour Steves, image review and DP for the reviews. I usually read every review pros and cons I can get my hands on. As far as which camera to buy, thats a good question. Honestly both cameras have their merits.
The 10D in low light on iso 800 and a 28-135IS lens is great and you can shoot down to 1/15 hand held and still get a good picture. My main complaint is the images are so soft you really have to work them hard. They are just plain fuzzy, but you would never get anyone from the canon forum to admit it.
The SD9 is not so great in low light, but when the light is good the sharpness excels every camera out except for the 14n and the 1ds. Some of the SD9 test portraits are awsome.
Personally I would like to have them both. Its just to bad the SD9 does not make a canon mount camera.
See if you can get your hands on both of them and try them out. With about 20-30 picture each. You can download photo pro for the SD9 and capture one has a 30 day trial period.
I hope this helps.
