For anyone interested, today I tested LilySpeech for myself.
It sucks in French, but on the other hand it works impressively well in English.
Even me who speaks it with rough corners, it types what I say flawlessly.
(I didn’t spend hours dictating in English, but for the time I’ve put in the test I was impressed. Enough so that I am now considering dictating my revision notes in English. – In French it is truly a depressing mess. ← I am being nice, here.)
Free, Open source, works under Windows.