Here is why it's stupid:
- Sous-vide doesn't get hot enough to kill botulism spores. Low acid foods will be very dangerous.
- Boiling is required for a strong seal on canning jars.
- All pectin jellies I have seen require boiling to set.
High acid recipes often call for processing in a water bath for a mere 10 minutes to seal the lids. Recipes that don't call for the water bath universally call for the product to be refrigerated.
Perhaps high acid foods could be vacuum sealed instead of bottled and pasteurized. It seems feasible but this is not the sort of thing you should experiment with. The failure conditions are catastrophic.
130F (approx. 54C) works great. That brings it to the very bottom of the "medium-rare scale", allowing you to sear before presentation without overcooking.
Although, I have to tell you, filet mignon is kind of a waste with sous vide. Not that it won't be great, but a much less expensive cut can be cooked at that temperature much longer and give you amazingly tender results.
The minimum time for a medium-rare filet would be just as long as it takes for the whole steak to reach 130F (half an hour or 45 minutes, depending on the thickness of the steak). Of course you can cook it longer, that's one of the beauties of sous vide, but that won't make it any better.
You can spend a whole bunch less money and get chuck (shoulder) and slice it into steaks. Sous vide it for two days at 130F, and that makes a steak almost as tender as filet, yet more flavorful.
That is my very first chuck steak cooked at 131F for two days, then seared. I used a NASA hot cast-iron pan for the searing, so 1°F less will give you a little bit more time to sear without risking overcooking your filet (which would be really tragic!).
Key Point: As Jefromi says in his answer, medium-rare is a scale. If you do 130F this time, consider carefully as you eat. Is the temperature absolutely perfect for you? Keep track of the temperatures you use every time you sous vide and your impressions at that temperature. Once you know what temperatures are perfect for you, sous vide allows you to duplicate perfection perfectly.
Best Answer
It depends on what you are planning to do.
If you want to get shelf-stable marmalade without a strict canning process, the answer is absolutely no. This kind of marmalade means that you're basically cooking a concentrated sugar syrup, and you have to keep it at the boiling point in an open vessel for a sufficient time for the water to evaporate.
If you want to use a modern marmalade recipe for canning, the answer is also practically no. Canning recipes have to be tested for safety, and are only safe if prepared exactly as prescribed. If it is made for stovetop, you can't guarantee that all relevant parameters will stay the same. Theoretically, it's conceivable that some experts will design a recipe specifically for sous vide and will test it properly before publishing it. If you have found such a recipe and trust it, then you could follow it. But I think they are very unlikely to exist, given the cost/benefit ratio of both the design process and of making the marmalade itself.
If shelf stability is not needed, then the answer becomes yes. You can experiment away with cooking a marmalade in a sous vide machine, either starting from a traditional stovetop recipe, or designing your own. From the viewpoint of food safety, the result will have to be kept in the fridge and eaten within 5 days.