Well, I have a cedar shake roof - I live in New England and they are EVERYWHERE, and all over the coast where they are exposed to harsh weather. (We are on the coast.) We inherited the roof, but were told by our contractor during our (ongoing) renovation that if kept properly sealed, it should last for 20+ years. We're not sure of the exact product used so that's a low end estimate. If it was a high end product it can last for 50+ years. I'm sure you'll get lots of responses from peeps who know the details but cedar in general resists rot. I totally believe the cedar saleswoman - they will last, especially if properly cared for. And yeah, I wouldn't trust the sales guy for the fake stuff because he's clearly trying to sell his product.

We were told to seal our roof every few years. It's an easy job, we hired it out and they sprayed it for I think $500.

There are vinyl products that look pretty good, but if they aren't in the colors you want, then that's that. Real cedar will of course be more maintenance than vinyl, since vinyl is virtually maintenance free. but that's a trade off - the real stuff is unmistakable and it's definitely a "look".

kit-
I live in the Pacific NW where we get a lot of rain and where cedar is widely used for roofs (shakes), and siding (shingles). I assume that you are using the term shingles to mean siding. My take on it is this. Newer cedar is not as long-lived as the stuff you used to get decades ago when a lot of the material was still coming from old growth. However, I only think this is a problem if you are using it for roofing in areas where you have a lot of debris falling on the roof from nearby trees. My first house, bought in 1974 had a cedar shake roof with at least 20 years on it by the time I replaced it; subsequent roofs lasted for about 12 years. However, the cedar siding I placed on it in 1979 still looks great because it's in a vertical application, well-sealed, and doesn't collect debris. Also, the pre-assembled panels of shingles that you are referring to are made of a good quality cedar, and look great. I agree that the vinyl can look somewhat phony. If I were you, I would have no problem going with the cedar shingle product. I think you will be happier with the appearance and the longevity, especially if you restain it every so often.

I should clarify that our roof is a mansard, and so almost vertical, which will certainly extend the life.

Also, cedar started to be used as siding in the 1800s, so is tried and true. I do agree that newer material is not the same as the old stuff b/c there isn't any more old growth but it's still a good choice. If it wasn't, then you wouldn't see the plethora of homes in NE still using it. It is literally everywhere. I don't notice these homes constantly being resided.

Alors, vous etes Quebequois(e)? ;-) La famille de mon mari est Quebequoise et la mienne est Americaine, mais je parle Francais, pas lui!

Honestly the only maintenance that I know of is treating it periodically, how often depending on the weather where you live. I believe if you are going to stain it, the staining has to be done more often.

Oui je suis Québécoise! :o) How funny it is to find french-speaking people on english forum, especially so when they are not from Quebec!
Thanks for your advices about the cedar, it helps me a lot. This is a hard decision to take!

For a period look and years of satisfaction I'd go with the cedar. New paints and stains are making painting and staining easier when it has to be done and if applied as directed can last a good long time. It also gives you the option of changing color should you grow bored with the choices you make this year. You can't say that about vinyl.

In a vertical or near-vertical application there is no maintenance other than periodic re-staining, and replacement if a shingle comes loose (rare). Bonne chance!

kit813,
There is no comparison between vinyl and cedar. The best vinyl siding looks pretty good new, but in a few years will look faded and tired. If you Google cedar shakes or cedar siding, you will find many companies in northeastern US and Canada which sell and ship traditional white cedar products. I know that there are here in Maine and in New Brunswick companies still producing traditional thick hand split cedar shakes - there may well be such companies in Quebec as well. These shakes are expensive, but they will last more than a lifetime and if you're willing to allow them to weather to their natural grey color, the maintenance is essentially zero.

Okay, so here is the quote! 11$ per square foot, for white cedar shingles with a double coat of stain applied in the factory, garanteed for 15 years 9stain) and 50 years (shingle).
Very high cost. And it is not installed at this cost lol But you are right the look and the quality is so different than vinyl, what I might just do is having the clapboard removed this summer, do the insulation job, prep it so it can past winter easily and then next summer do the siding.