Is this worth the upgrade?

I currently shoot woth a 40D and have been considering the purchase of a new camera and keeping the 40D as a backup. I shoot primarily seniors and family sessions and am not concerned about losing shutter speed.

I would like to go full frame with my next camera.

Sell the 40D and and replace it with the 5DC
Sell my 10-22 and replace it with a 17-40L

Is replacing the 40D with a 5dc worth the hassle?

In short, yes. Especially if you shoot mainly portraits.

I agree if you are mainly a portraiture photographer, you will likely be happier with a 5dc.

You might also wait a few months and get a 5d2 that will lower in price when the 5d3 is released.

yes, the 5dc would be a good fit for what shoot

I have both and a similar lens line up to you ,the 24/105 is a different animal on a 5D compared with a 40D and you would be surprised at how wide it is! and the 70/200 shines on the 5D.
My 40D is getting an outing tomorrow as I am shooting motor sport and want the frame rate and crop factor but otherwise it rarely gets used.
The only downside I found with the 5D is the screen ( and then only once), having used a 5DMk 11 the screen is a lot better but I can,t justify £1700 for a better screen.
If you can afford to keep the 40D then do so, if you do get a 5D then I would hold off on the 17/40 as you may find you don,t need it.

I had a Rebel XT (Still do) and I bought my 5D Mark II so I can do more professional style work in doors. The problem is I had a 10-20 Sigma that I LOVED using with the Rebel but I could no longer use it on the 5D. So my dilemma was after using the 5D for a couple months I went back to use the Rebel to shoot with the 10-20 and hated using the Rebel (Got spoiled by the 5D). So I started looking for a suitable Crop sensor camera and heard all kinds of great stuff about the 40D. So I purchased a 40D off eBay for $250 and it's been the perfect companion with the 10-20 Sigma as well as my 25-105, 50, and other lenses.

The 40D is my backup camera at weddings and it is also my carry around camera (probably not a good idea to carry around my backup camera but until I get another body, that's the carry around).

So, I would say that while buying a 5Dc would be a great investment, I would hang on to the 40D with the crop lenses and start a new kit with FF sensor lenses. If your budget allows this.

Personally I'd get a 5DII instead of 5DC, but my needs might be different than yours and it's certainly cheaper to consider the classic model.

While the AF and metering systems are essentially unchanged, 5DII has self-cleaning sensor, 14 bit vs 12 bit, nicer LCD (bigger, brighter, higher resolution), mirror that's more securely affixed, ISO range that goes three full stops higher (25600 vs 3200), Live View and other features that make it worthwhile IMHO. I don't use it personally, but you might appreciate it's HD video too. It's also about 3 year old technology vs 6 year old. 5DC is a couple years older model than your 40D. So I'm not sure I'd call it a big upgrade to go to 5DC.... Though it would be to go to 5DII.

Not that 5DC isn't a really capable camera, if you can find a good, solid, low mileage copy that's had the mirror fix done. I'd also suggest trying to keep your 40D and adding the FF camera, instead of replacing it.

You don't need to build a whole new kit of lenses for use on FF.... You really only need to add one lens... wide angle. I don't use an UWA zoom on FF.... Instead I use 20/2.8 prime. That's plenty wide for me and has less distortions. There are various other options, of course.

Your 50/1.4 and 85/1.8 will work very nicely on FF. Personally I consider 135mm an essential focal length on FF and Canon's f2L is a superb lens. I ordered one the same time I got the 5DII.

40D, 7D, 5DII here.

40D and 5DII make a great combo. I like having a crop an inexpensive body, a crop at that, as a backup.

The 5Dc is an even older design than the 40D. It can be annoying, starting from the lack of sensor cleaning.

If you end up going with a 35mm sensor I don't see why you would need the 17-40L given you have the 24-105L.

As mentioned the most promising combo in that financial envelope probably is the 135L on the 5d2.