I've worked in a few places that used the sous vide method. Its becoming quite popluar in fancy restaurants as a way to cook foods to perfect doneness.
From a culinary perspective its an amazing way to cook and produces consistent products, it adds another dimension to a chefs repertoire that can make for great food.
That said, from a health perspective, I would avoid it like the plague. Chefs tend to want to manipulate food in many different ways to coax as much flavor out of food. Which is why they cook things in so much oil, brown everything, loads of salt and sugar, msg, etc...So this is really just trading one method of unhealthy cooking for another. Heating liquid oils, at all, produces some nasty carcinogens and oxidised lipid with goes on to produce AGE's in our bodies. But then cooking sous vide leaches various petrochemicals into the food. And usually restaurants that would do sous vide will also do the frying/flavoring of the same food, so you are getting a double whammy...
Also, they are likely planning on cooking foods sous vide that have alcohol, acid, or fat...all of which leach compounds out of plastics even faster than water (see study below).
The cooking times will likely vary from 30 minutes to 2 days when cooking sous vide, and the longer the time and the higher the temperature, the more compounds will be leached from the plastic.
Plus, this is another expensive piece of equipment that can be marketed to chefs and customers...so this is just another way to make a buck, without really having a concern for the customers best health. (restaurants weren't designed for that, your own kitchen is...)
This is some of the reasoning behind my recommendations that people really concerned about their health should avoid eating out at restaurants altogether (no matter the quality or promoted health benefits). Yes, extreme, but you would be surprised as to what other kind of contamination happens in the best of restaurants...trust me.
Here is some background on what I'm talking about...
Sous vide cooking products
The plastic bags used in sous vide are likely made of PET (or HDPE) so here is a report on the leaching of a specific chemical at low temperatures. Even thought the EPA has set standards for contamination levels of such products, if these compounds are toxic at all, why would it be ok at ANY level, especially one with a carcinogenic level as low as 6ppb!
There is another way to cook sous vide which is much healthier, yet hasn't seen professional applications. There is a way to vacuum seal glass jars and cook sous vide. Glass is a better conductor of heat and is less of a source of contamination and has zero leaching (plus they are 100% reusable/recyclable ).
Blog of a Therapeutic Chef
Adventures, discoveries, experiences, opinions, and mistakes in the world of food, faith and farming