Hi Fabien,
Welcome to the Dharma Overground.
Good question. I was put off when first reading Daniel Ingram's essays and book. Talking about actual progress in meditation, as opposed to worshipping ideals, is such a huge taboo in Buddhism. After some time, I realized that I had two options if i wanted to find out for myself rather than just believe Daniel's claims or someone else's:
Prove those guys wrong who claimed that progress was rare or impossible, or
disprove Daniel Ingram's claim that progress was to be expected for those who practice well.
I decided that it was more empowering to assume progress was to be expected

I also saw that this was in line with the Buddha's teaching. And after practicing for some weeks, I noticed how astonishingly precise the "maps" were; and those aren't Daniel's inventions either.
So, don't get stuck deciding whose opinion to adopt for your own: do it, see for yourself, discuss it here. Misinterpretations of meditation experiences are only serious when not talked about. Comparing results quickly puts things in perspective, at least for me.
Cheers,
Florian