Wouldn’t it be easier to just use a crockpot with a temp probe?
I've used this method to precook apples for apple pie. It causes them to hold up better during baking phase, and prevents some oxidation.
There are some flaws to this method that are obvious. First it's named in French. The method wasn't invented in France, it wasn't pioneered in France, the first commercial applications weren't done in France, and the first commercially made machines weren't made in France. Why a French name? It just pissed me off.
Another important issue to note is that you can't brown anything using this method. The Malliard effect (yes, named after a Frenchie, but he at least deserved it) dramatically changes the flavor of many items (for the better) and in my mind is a requirement for most meat and a lot of vegetables.
Can you imagine Beef Bourguignon (a classic French dish) without the Malliard effect?
When you take into account the weaknesses of the vacuum water convection method it's a very situational cooking technique.