My friends and I (8 of us total) stayed at Francois' place for 4 nights for my birthday and it was perfect.
The place was sparkling clean, extremely secure, and in the best possible location (just steps away from the Moulin Rouge, Sacre Couer, and a wide range of restaurants and bars).
Francois was also very communicative throughout the whole trip and went above and beyond to make sure our stay was comfortable. He even let us check in early and leave our bags at the place late to make things easier for us.
If you're coming to Montmartre with a family or a big group, I highly recommend this place!